libavformat/avisynth.c - third_party/ffmpeg - Git at Google

 /*
  * Avi/AvxSynth support
  * Copyright (c) 2012 AvxSynth Team.
  *
  * This file is part of FFmpeg
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #include "avformat.h"
 #include "internal.h"
 #include "libavcodec/internal.h"

 // Enable function pointer definitions for runtime loading.
 #define AVSC_NO_DECLSPEC

 // Shut up ffmpeg error messages.
 // avisynth_c.h contains inline functions that call these functions.
 #undef malloc
 #undef free
 #undef printf

 // Platform-specific directives for AviSynth vs AvxSynth.
 #ifdef _WIN32
   #include <windows.h>
   #undef EXTERN_C
   #include "compat/avisynth/avisynth_c.h"
   #include "compat/avisynth/avisynth_c_25.h"
   #define AVISYNTH_LIB "avisynth"
 #else
   #include <dlfcn.h>
   #include "compat/avisynth/avxsynth_c.h"
    #if defined (__APPLE__)
      #define AVISYNTH_LIB "libavxsynth.dylib"
    #else
      #define AVISYNTH_LIB "libavxsynth.so"
    #endif

   #define LoadLibrary(x) dlopen(x, RTLD_NOW | RTLD_GLOBAL)
   #define GetProcAddress dlsym
   #define FreeLibrary dlclose
 #endif

 // AvxSynth doesn't have these colorspaces, so disable them
 #ifndef _WIN32
 #define avs_is_yv24(vi) 0
 #define avs_is_yv16(vi) 0
 #define avs_is_yv411(vi) 0
 #define avs_is_y8(vi) 0
 #endif

 typedef struct {
     void *library;
 #define AVSC_DECLARE_FUNC(name) name##_func name
     AVSC_DECLARE_FUNC(avs_bit_blt);
     AVSC_DECLARE_FUNC(avs_clip_get_error);
     AVSC_DECLARE_FUNC(avs_create_script_environment);
     AVSC_DECLARE_FUNC(avs_delete_script_environment);
     AVSC_DECLARE_FUNC(avs_get_audio);
     AVSC_DECLARE_FUNC(avs_get_error);
     AVSC_DECLARE_FUNC(avs_get_frame);
     AVSC_DECLARE_FUNC(avs_get_version);
     AVSC_DECLARE_FUNC(avs_get_video_info);
     AVSC_DECLARE_FUNC(avs_invoke);
     AVSC_DECLARE_FUNC(avs_release_clip);
     AVSC_DECLARE_FUNC(avs_release_value);
     AVSC_DECLARE_FUNC(avs_release_video_frame);
     AVSC_DECLARE_FUNC(avs_take_clip);
 #undef AVSC_DECLARE_FUNC
 } AviSynthLibrary;

 struct AviSynthContext {
     AVS_ScriptEnvironment *env;
     AVS_Clip *clip;
     const AVS_VideoInfo *vi;

     // avisynth_read_packet_video() iterates over this.
     int n_planes;
     const int *planes;

     int curr_stream;
     int curr_frame;
     int64_t curr_sample;

     int error;

     // Linked list pointers.
     struct AviSynthContext *next;
 };
 typedef struct AviSynthContext AviSynthContext;

 static const int avs_planes_packed[1] = {0};
 static const int avs_planes_grey[1] = {AVS_PLANAR_Y};
 static const int avs_planes_yuv[3] = {AVS_PLANAR_Y, AVS_PLANAR_U, AVS_PLANAR_V};

 // A conflict between C++ global objects, atexit, and dynamic loading requires
 // us to register our own atexit handler to prevent double freeing.
 static AviSynthLibrary *avs_library = NULL;
 static int avs_atexit_called = 0;

 // Linked list of AviSynthContexts. An atexit handler destroys this list.
 static AviSynthContext *avs_ctx_list = NULL;

 static av_cold void avisynth_atexit_handler(void);

 static av_cold int avisynth_load_library(void) {
     avs_library = av_mallocz(sizeof(AviSynthLibrary));
     if (!avs_library)
         return AVERROR_UNKNOWN;

     avs_library->library = LoadLibrary(AVISYNTH_LIB);
     if (!avs_library->library)
         goto init_fail;

 #define LOAD_AVS_FUNC(name, continue_on_fail) \
 { \
     avs_library->name = (void*)GetProcAddress(avs_library->library, #name); \
     if(!continue_on_fail && !avs_library->name) \
         goto fail; \
 }
     LOAD_AVS_FUNC(avs_bit_blt, 0);
     LOAD_AVS_FUNC(avs_clip_get_error, 0);
     LOAD_AVS_FUNC(avs_create_script_environment, 0);
     LOAD_AVS_FUNC(avs_delete_script_environment, 0);
     LOAD_AVS_FUNC(avs_get_audio, 0);
     LOAD_AVS_FUNC(avs_get_error, 1); // New to AviSynth 2.6
     LOAD_AVS_FUNC(avs_get_frame, 0);
     LOAD_AVS_FUNC(avs_get_version, 0);
     LOAD_AVS_FUNC(avs_get_video_info, 0);
     LOAD_AVS_FUNC(avs_invoke, 0);
     LOAD_AVS_FUNC(avs_release_clip, 0);
     LOAD_AVS_FUNC(avs_release_value, 0);
     LOAD_AVS_FUNC(avs_release_video_frame, 0);
     LOAD_AVS_FUNC(avs_take_clip, 0);
 #undef LOAD_AVS_FUNC

     atexit(avisynth_atexit_handler);
     return 0;

 fail:
     FreeLibrary(avs_library->library);
 init_fail:
     av_freep(&avs_library);
     return AVERROR_UNKNOWN;
 }

 // Note that avisynth_context_create and avisynth_context_destroy
 // do not allocate or free the actual context! That is taken care of
 // by libavformat.
 static av_cold int avisynth_context_create(AVFormatContext *s) {
     AviSynthContext *avs = (AviSynthContext *)s->priv_data;
     int ret;

     if (!avs_library) {
         if (ret = avisynth_load_library())
             return ret;
     }

     avs->env = avs_library->avs_create_script_environment(3);
     if (avs_library->avs_get_error) {
         const char *error = avs_library->avs_get_error(avs->env);
         if (error) {
             av_log(s, AV_LOG_ERROR, "%s\n", error);
             return AVERROR_UNKNOWN;
         }
     }

     if (!avs_ctx_list) {
         avs_ctx_list = avs;
     } else {
         avs->next = avs_ctx_list;
         avs_ctx_list = avs;
     }

     return 0;
 }

 static av_cold void avisynth_context_destroy(AviSynthContext *avs) {
     if (avs_atexit_called)
        return;

     if (avs == avs_ctx_list) {
         avs_ctx_list = avs->next;
     } else {
         AviSynthContext *prev = avs_ctx_list;
         while (prev->next != avs)
             prev = prev->next;
         prev->next = avs->next;
     }

     if (avs->clip) {
         avs_library->avs_release_clip(avs->clip);
         avs->clip = NULL;
     }
     if (avs->env) {
         avs_library->avs_delete_script_environment(avs->env);
         avs->env = NULL;
     }
 }

 static av_cold void avisynth_atexit_handler(void) {
     AviSynthContext *avs = avs_ctx_list;

     while (avs) {
         AviSynthContext *next = avs->next;
         avisynth_context_destroy(avs);
         avs = next;
     }
     FreeLibrary(avs_library->library);
     av_freep(&avs_library);

     avs_atexit_called = 1;
 }

 // Create AVStream from audio and video data.
 static int avisynth_create_stream_video(AVFormatContext *s, AVStream *st) {
     AviSynthContext *avs = s->priv_data;
     int planar = 0; // 0: packed, 1: YUV, 2: Y8

     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
     st->codec->codec_id = CODEC_ID_RAWVIDEO;
     st->codec->width = avs->vi->width;
     st->codec->height = avs->vi->height;

     st->time_base = (AVRational) {avs->vi->fps_denominator, avs->vi->fps_numerator};
     st->avg_frame_rate = (AVRational) {avs->vi->fps_numerator, avs->vi->fps_denominator};
     st->start_time = 0;
     st->duration = avs->vi->num_frames;
     st->nb_frames = avs->vi->num_frames;

     switch (avs->vi->pixel_type) {
 #ifdef _WIN32
     case AVS_CS_YV24:
         st->codec->pix_fmt = AV_PIX_FMT_YUV444P;
         planar = 1;
         break;
     case AVS_CS_YV16:
         st->codec->pix_fmt = AV_PIX_FMT_YUV422P;
         planar = 1;
         break;
     case AVS_CS_YV411:
         st->codec->pix_fmt = AV_PIX_FMT_YUV411P;
         planar = 1;
         break;
     case AVS_CS_Y8:
         st->codec->pix_fmt = AV_PIX_FMT_GRAY8;
         planar = 2;
         break;
 #endif
     case AVS_CS_BGR24:
         st->codec->pix_fmt = AV_PIX_FMT_BGR24;
         break;
     case AVS_CS_BGR32:
         st->codec->pix_fmt = AV_PIX_FMT_RGB32;
         break;
     case AVS_CS_YUY2:
         st->codec->pix_fmt = AV_PIX_FMT_YUYV422;
         break;
     case AVS_CS_YV12:
         st->codec->pix_fmt = AV_PIX_FMT_YUV420P;
         planar = 1;
         break;
     case AVS_CS_I420: // Is this even used anywhere?
         st->codec->pix_fmt = AV_PIX_FMT_YUV420P;
         planar = 1;
         break;
     default:
         av_log(s, AV_LOG_ERROR, "unknown AviSynth colorspace %d\n", avs->vi->pixel_type);
         avs->error = 1;
         return AVERROR_UNKNOWN;
     }

     switch (planar) {
     case 2: // Y8
         avs->n_planes = 1;
         avs->planes = avs_planes_grey;
         break;
     case 1: // YUV
         avs->n_planes = 3;
         avs->planes = avs_planes_yuv;
         break;
     default:
         avs->n_planes = 1;
         avs->planes = avs_planes_packed;
     }
     return 0;
 }

 static int avisynth_create_stream_audio(AVFormatContext *s, AVStream *st) {
     AviSynthContext *avs = s->priv_data;

     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
     st->codec->sample_rate = avs->vi->audio_samples_per_second;
     st->codec->channels = avs->vi->nchannels;
     st->time_base = (AVRational) {1, avs->vi->audio_samples_per_second};

     switch (avs->vi->sample_type) {
     case AVS_SAMPLE_INT8:
         st->codec->codec_id = CODEC_ID_PCM_U8;
         break;
     case AVS_SAMPLE_INT16:
         st->codec->codec_id = CODEC_ID_PCM_S16LE;
         break;
     case AVS_SAMPLE_INT24:
         st->codec->codec_id = CODEC_ID_PCM_S24LE;
         break;
     case AVS_SAMPLE_INT32:
         st->codec->codec_id = CODEC_ID_PCM_S32LE;
         break;
     case AVS_SAMPLE_FLOAT:
         st->codec->codec_id = CODEC_ID_PCM_F32LE;
         break;
     default:
         av_log(s, AV_LOG_ERROR, "unknown AviSynth sample type %d\n", avs->vi->sample_type);
         avs->error = 1;
         return AVERROR_UNKNOWN;
     }
     return 0;
 }

 static int avisynth_create_stream(AVFormatContext *s) {
     AviSynthContext *avs = s->priv_data;
     AVStream *st;
     int ret;
     int id = 0;

     if (avs_has_video(avs->vi)) {
         st = avformat_new_stream(s, NULL);
         if (!st)
             return AVERROR_UNKNOWN;
         st->id = id++;
         if (ret = avisynth_create_stream_video(s, st))
             return ret;
     }
     if (avs_has_audio(avs->vi)) {
         st = avformat_new_stream(s, NULL);
         if (!st)
             return AVERROR_UNKNOWN;
         st->id = id++;
         if (ret = avisynth_create_stream_audio(s, st))
             return ret;
     }
     return 0;
 }

 static int avisynth_open_file(AVFormatContext *s) {
     AviSynthContext *avs = (AviSynthContext *)s->priv_data;
     AVS_Value arg, val;
     int ret;
 #ifdef _WIN32
     char filename_ansi[MAX_PATH * 4];
     wchar_t filename_wc[MAX_PATH * 4];
 #endif

     if (ret = avisynth_context_create(s))
         return ret;

 #ifdef _WIN32
     // Convert UTF-8 to ANSI code page
     MultiByteToWideChar(CP_UTF8, 0, s->filename, -1, filename_wc, MAX_PATH * 4);
     WideCharToMultiByte(CP_THREAD_ACP, 0, filename_wc, -1, filename_ansi, MAX_PATH * 4, NULL, NULL);
     arg = avs_new_value_string(filename_ansi);
 #else
     arg = avs_new_value_string(s->filename);
 #endif
     val = avs_library->avs_invoke(avs->env, "Import", arg, 0);
     if (avs_is_error(val)) {
         av_log(s, AV_LOG_ERROR, "%s\n", avs_as_error(val));
         ret = AVERROR_UNKNOWN;
         goto fail;
     }
     if (!avs_is_clip(val)) {
         av_log(s, AV_LOG_ERROR, "%s\n", "AviSynth script did not return a clip");
         ret = AVERROR_UNKNOWN;
         goto fail;
     }

     avs->clip = avs_library->avs_take_clip(val, avs->env);
     avs->vi = avs_library->avs_get_video_info(avs->clip);

     // Release the AVS_Value as it will go out of scope.
     avs_library->avs_release_value(val);

     if (ret = avisynth_create_stream(s))
         goto fail;

     return 0;

 fail:
     avisynth_context_destroy(avs);
     return ret;
 }

 static void avisynth_next_stream(AVFormatContext *s, AVStream **st, AVPacket *pkt, int *discard) {
     AviSynthContext *avs = s->priv_data;

     pkt->stream_index = avs->curr_stream++;
     avs->curr_stream %= s->nb_streams;

     *st = s->streams[pkt->stream_index];
     if ((*st)->discard == AVDISCARD_ALL)
         *discard = 1;
     else
         *discard = 0;

     return;
 }

 // Copy AviSynth clip data into an AVPacket.
 static int avisynth_read_packet_video(AVFormatContext *s, AVPacket *pkt, int discard) {
     AviSynthContext *avs = s->priv_data;
     AVS_VideoFrame *frame;
     unsigned char *dst_p;
     const unsigned char *src_p;
     int n, i, plane, rowsize, planeheight, pitch, bits;
     const char *error;

     if (avs->curr_frame >= avs->vi->num_frames)
         return AVERROR_EOF;

     // This must happen even if the stream is discarded to prevent desync.
     n = avs->curr_frame++;
     if (discard)
         return 0;

     pkt->pts = n;
     pkt->dts = n;
     pkt->duration = 1;

     // Define the bpp values for the new AviSynth 2.6 colorspaces
     if (avs_is_yv24(avs->vi)) {
         bits = 24;
     } else if (avs_is_yv16(avs->vi)) {
         bits = 16;
     } else if (avs_is_yv411(avs->vi)) {
         bits = 12;
     } else if (avs_is_y8(avs->vi)) {
         bits = 8;
     } else {
         bits = avs_bits_per_pixel(avs->vi);
     }

     // Without cast to int64_t, calculation overflows at about 9k x 9k resolution.
     pkt->size = (((int64_t)avs->vi->width * (int64_t)avs->vi->height) * bits) / 8;
     if (!pkt->size)
         return AVERROR_UNKNOWN;
     pkt->data = av_malloc(pkt->size);
     if (!pkt->data)
         return AVERROR_UNKNOWN;

     frame = avs_library->avs_get_frame(avs->clip, n);
     error = avs_library->avs_clip_get_error(avs->clip);
     if (error) {
         av_log(s, AV_LOG_ERROR, "%s\n", error);
         avs->error = 1;
         av_freep(&pkt->data);
         return AVERROR_UNKNOWN;
     }

     dst_p = pkt->data;
     for (i = 0; i < avs->n_planes; i++) {
         plane = avs->planes[i];
         src_p = avs_get_read_ptr_p(frame, plane);
         pitch = avs_get_pitch_p(frame, plane);

 #ifdef _WIN32
         if (avs_library->avs_get_version(avs->clip) == 3) {
             rowsize = avs_get_row_size_p_25(frame, plane);
             planeheight = avs_get_height_p_25(frame, plane);
         } else {
             rowsize = avs_get_row_size_p(frame, plane);
             planeheight = avs_get_height_p(frame, plane);
         }
 #else
         rowsize = avs_get_row_size_p(frame, plane);
         planeheight = avs_get_height_p(frame, plane);
 #endif

         // Flip RGB video.
         if (avs_is_rgb24(avs->vi) || avs_is_rgb(avs->vi)) {
             src_p = src_p + (planeheight - 1) * pitch;
             pitch = -pitch;
         }

         avs_library->avs_bit_blt(avs->env, dst_p, rowsize, src_p, pitch, rowsize, planeheight);
         dst_p += rowsize * planeheight;
     }

     avs_library->avs_release_video_frame(frame);
     return 0;
 }

 static int avisynth_read_packet_audio(AVFormatContext *s, AVPacket *pkt, int discard) {
     AviSynthContext *avs = s->priv_data;
     AVRational fps, samplerate;
     int samples;
     int64_t n;
     const char *error;

     if (avs->curr_sample >= avs->vi->num_audio_samples)
         return AVERROR_EOF;

     fps.num = avs->vi->fps_numerator;
     fps.den = avs->vi->fps_denominator;
     samplerate.num = avs->vi->audio_samples_per_second;
     samplerate.den = 1;

     if (avs_has_video(avs->vi)) {
         if (avs->curr_frame < avs->vi->num_frames)
             samples = av_rescale_q(avs->curr_frame, samplerate, fps) - avs->curr_sample;
         else
             samples = av_rescale_q(1, samplerate, fps);
     } else {
         samples = 1000;
     }

     // After seeking, audio may catch up with video.
     if (samples <= 0) {
         pkt->size = 0;
         pkt->data = NULL;
         return 0;
     }

     if (avs->curr_sample + samples > avs->vi->num_audio_samples)
         samples = avs->vi->num_audio_samples - avs->curr_sample;

     // This must happen even if the stream is discarded to prevent desync.
     n = avs->curr_sample;
     avs->curr_sample += samples;
     if (discard)
         return 0;

     pkt->pts = n;
     pkt->dts = n;
     pkt->duration = samples;

     pkt->size = avs_bytes_per_channel_sample(avs->vi) * samples * avs->vi->nchannels;
     if (!pkt->size)
         return AVERROR_UNKNOWN;
     pkt->data = av_malloc(pkt->size);
     if (!pkt->data)
         return AVERROR_UNKNOWN;

     avs_library->avs_get_audio(avs->clip, pkt->data, n, samples);
     error = avs_library->avs_clip_get_error(avs->clip);
     if (error) {
         av_log(s, AV_LOG_ERROR, "%s\n", error);
         avs->error = 1;
         av_freep(&pkt->data);
         return AVERROR_UNKNOWN;
     }
     return 0;
 }

 static av_cold int avisynth_read_header(AVFormatContext *s) {
     int ret;

     // Calling library must implement a lock for thread-safe opens.
     if (ret = avpriv_lock_avformat())
         return ret;

     if (ret = avisynth_open_file(s)) {
         avpriv_unlock_avformat();
         return ret;
     }

     avpriv_unlock_avformat();
     return 0;
 }

 static int avisynth_read_packet(AVFormatContext *s, AVPacket *pkt) {
     AviSynthContext *avs = s->priv_data;
     AVStream *st;
     int discard = 0;
     int ret;

     if (avs->error)
         return AVERROR_UNKNOWN;

     pkt->destruct = av_destruct_packet;

     // If either stream reaches EOF, try to read the other one before giving up.
     avisynth_next_stream(s, &st, pkt, &discard);
     if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
         ret = avisynth_read_packet_video(s, pkt, discard);
         if (ret == AVERROR_EOF && avs_has_audio(avs->vi)) {
             avisynth_next_stream(s, &st, pkt, &discard);
             return avisynth_read_packet_audio(s, pkt, discard);
         }
         return ret;
     } else {
         ret = avisynth_read_packet_audio(s, pkt, discard);
         if (ret == AVERROR_EOF && avs_has_video(avs->vi)) {
             avisynth_next_stream(s, &st, pkt, &discard);
             return avisynth_read_packet_video(s, pkt, discard);
         }
         return ret;
     }
 }

 static av_cold int avisynth_read_close(AVFormatContext *s) {
     if (avpriv_lock_avformat())
         return AVERROR_UNKNOWN;

     avisynth_context_destroy(s->priv_data);
     avpriv_unlock_avformat();
     return 0;
 }

 static int avisynth_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
     AviSynthContext *avs = s->priv_data;
     AVStream *st;
     AVRational fps, samplerate;

     if (avs->error)
         return AVERROR_UNKNOWN;

     fps = (AVRational) {avs->vi->fps_numerator, avs->vi->fps_denominator};
     samplerate = (AVRational) {avs->vi->audio_samples_per_second, 1};

     st = s->streams[stream_index];
     if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
         // AviSynth frame counts are signed int.
         if ((timestamp >= avs->vi->num_frames) || (timestamp > INT_MAX) || (timestamp < 0))
             return AVERROR_EOF;
         avs->curr_frame = timestamp;
         if (avs_has_audio(avs->vi))
             avs->curr_sample = av_rescale_q(timestamp, samplerate, fps);
     } else {
         if ((timestamp >= avs->vi->num_audio_samples) || (timestamp < 0))
             return AVERROR_EOF;
         // Force frame granularity for seeking.
         if (avs_has_video(avs->vi)) {
             avs->curr_frame = av_rescale_q(timestamp, fps, samplerate);
             avs->curr_sample = av_rescale_q(avs->curr_frame, samplerate, fps);
         } else {
             avs->curr_sample = timestamp;
         }
     }

     return 0;
 }

 AVInputFormat ff_avisynth_demuxer = {
     .name           = "avisynth",
     .long_name      = NULL_IF_CONFIG_SMALL("AviSynth script"),
     .priv_data_size = sizeof(AviSynthContext),
     .read_header    = avisynth_read_header,
     .read_packet    = avisynth_read_packet,
     .read_close     = avisynth_read_close,
     .read_seek      = avisynth_read_seek,
     .extensions     = "avs",
 };
	/*
	* Avi/AvxSynth support
	* Copyright (c) 2012 AvxSynth Team.
	*
	* This file is part of FFmpeg
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include "avformat.h"
	#include "internal.h"
	#include "libavcodec/internal.h"

	// Enable function pointer definitions for runtime loading.
	#define AVSC_NO_DECLSPEC

	// Shut up ffmpeg error messages.
	// avisynth_c.h contains inline functions that call these functions.
	#undef malloc
	#undef free
	#undef printf

	// Platform-specific directives for AviSynth vs AvxSynth.
	#ifdef _WIN32
	#include <windows.h>
	#undef EXTERN_C
	#include "compat/avisynth/avisynth_c.h"
	#include "compat/avisynth/avisynth_c_25.h"
	#define AVISYNTH_LIB "avisynth"
	#else
	#include <dlfcn.h>
	#include "compat/avisynth/avxsynth_c.h"
	#if defined (__APPLE__)
	#define AVISYNTH_LIB "libavxsynth.dylib"
	#else
	#define AVISYNTH_LIB "libavxsynth.so"
	#endif

	#define LoadLibrary(x) dlopen(x, RTLD_NOW \| RTLD_GLOBAL)
	#define GetProcAddress dlsym
	#define FreeLibrary dlclose
	#endif

	// AvxSynth doesn't have these colorspaces, so disable them
	#ifndef _WIN32
	#define avs_is_yv24(vi) 0
	#define avs_is_yv16(vi) 0
	#define avs_is_yv411(vi) 0
	#define avs_is_y8(vi) 0
	#endif

	typedef struct {
	void *library;
	#define AVSC_DECLARE_FUNC(name) name##_func name
	AVSC_DECLARE_FUNC(avs_bit_blt);
	AVSC_DECLARE_FUNC(avs_clip_get_error);
	AVSC_DECLARE_FUNC(avs_create_script_environment);
	AVSC_DECLARE_FUNC(avs_delete_script_environment);
	AVSC_DECLARE_FUNC(avs_get_audio);
	AVSC_DECLARE_FUNC(avs_get_error);
	AVSC_DECLARE_FUNC(avs_get_frame);
	AVSC_DECLARE_FUNC(avs_get_version);
	AVSC_DECLARE_FUNC(avs_get_video_info);
	AVSC_DECLARE_FUNC(avs_invoke);
	AVSC_DECLARE_FUNC(avs_release_clip);
	AVSC_DECLARE_FUNC(avs_release_value);
	AVSC_DECLARE_FUNC(avs_release_video_frame);
	AVSC_DECLARE_FUNC(avs_take_clip);
	#undef AVSC_DECLARE_FUNC
	} AviSynthLibrary;

	struct AviSynthContext {
	AVS_ScriptEnvironment *env;
	AVS_Clip *clip;
	const AVS_VideoInfo *vi;

	// avisynth_read_packet_video() iterates over this.
	int n_planes;
	const int *planes;

	int curr_stream;
	int curr_frame;
	int64_t curr_sample;

	int error;

	// Linked list pointers.
	struct AviSynthContext *next;
	};
	typedef struct AviSynthContext AviSynthContext;

	static const int avs_planes_packed[1] = {0};
	static const int avs_planes_grey[1] = {AVS_PLANAR_Y};
	static const int avs_planes_yuv[3] = {AVS_PLANAR_Y, AVS_PLANAR_U, AVS_PLANAR_V};

	// A conflict between C++ global objects, atexit, and dynamic loading requires
	// us to register our own atexit handler to prevent double freeing.
	static AviSynthLibrary *avs_library = NULL;
	static int avs_atexit_called = 0;

	// Linked list of AviSynthContexts. An atexit handler destroys this list.
	static AviSynthContext *avs_ctx_list = NULL;

	static av_cold void avisynth_atexit_handler(void);

	static av_cold int avisynth_load_library(void) {
	avs_library = av_mallocz(sizeof(AviSynthLibrary));
	if (!avs_library)
	return AVERROR_UNKNOWN;

	avs_library->library = LoadLibrary(AVISYNTH_LIB);
	if (!avs_library->library)
	goto init_fail;

	#define LOAD_AVS_FUNC(name, continue_on_fail) \
	{ \
	avs_library->name = (void*)GetProcAddress(avs_library->library, #name); \
	if(!continue_on_fail && !avs_library->name) \
	goto fail; \
	}
	LOAD_AVS_FUNC(avs_bit_blt, 0);
	LOAD_AVS_FUNC(avs_clip_get_error, 0);
	LOAD_AVS_FUNC(avs_create_script_environment, 0);
	LOAD_AVS_FUNC(avs_delete_script_environment, 0);
	LOAD_AVS_FUNC(avs_get_audio, 0);
	LOAD_AVS_FUNC(avs_get_error, 1); // New to AviSynth 2.6
	LOAD_AVS_FUNC(avs_get_frame, 0);
	LOAD_AVS_FUNC(avs_get_version, 0);
	LOAD_AVS_FUNC(avs_get_video_info, 0);
	LOAD_AVS_FUNC(avs_invoke, 0);
	LOAD_AVS_FUNC(avs_release_clip, 0);
	LOAD_AVS_FUNC(avs_release_value, 0);
	LOAD_AVS_FUNC(avs_release_video_frame, 0);
	LOAD_AVS_FUNC(avs_take_clip, 0);
	#undef LOAD_AVS_FUNC

	atexit(avisynth_atexit_handler);
	return 0;

	fail:
	FreeLibrary(avs_library->library);
	init_fail:
	av_freep(&avs_library);
	return AVERROR_UNKNOWN;
	}

	// Note that avisynth_context_create and avisynth_context_destroy
	// do not allocate or free the actual context! That is taken care of
	// by libavformat.
	static av_cold int avisynth_context_create(AVFormatContext *s) {
	AviSynthContext avs = (AviSynthContext )s->priv_data;
	int ret;

	if (!avs_library) {
	if (ret = avisynth_load_library())
	return ret;
	}

	avs->env = avs_library->avs_create_script_environment(3);
	if (avs_library->avs_get_error) {
	const char *error = avs_library->avs_get_error(avs->env);
	if (error) {
	av_log(s, AV_LOG_ERROR, "%s\n", error);
	return AVERROR_UNKNOWN;
	}
	}

	if (!avs_ctx_list) {
	avs_ctx_list = avs;
	} else {
	avs->next = avs_ctx_list;
	avs_ctx_list = avs;
	}

	return 0;
	}

	static av_cold void avisynth_context_destroy(AviSynthContext *avs) {
	if (avs_atexit_called)
	return;

	if (avs == avs_ctx_list) {
	avs_ctx_list = avs->next;
	} else {
	AviSynthContext *prev = avs_ctx_list;
	while (prev->next != avs)
	prev = prev->next;
	prev->next = avs->next;
	}

	if (avs->clip) {
	avs_library->avs_release_clip(avs->clip);
	avs->clip = NULL;
	}
	if (avs->env) {
	avs_library->avs_delete_script_environment(avs->env);
	avs->env = NULL;
	}
	}

	static av_cold void avisynth_atexit_handler(void) {
	AviSynthContext *avs = avs_ctx_list;

	while (avs) {
	AviSynthContext *next = avs->next;
	avisynth_context_destroy(avs);
	avs = next;
	}
	FreeLibrary(avs_library->library);
	av_freep(&avs_library);

	avs_atexit_called = 1;
	}

	// Create AVStream from audio and video data.
	static int avisynth_create_stream_video(AVFormatContext s, AVStream st) {
	AviSynthContext *avs = s->priv_data;
	int planar = 0; // 0: packed, 1: YUV, 2: Y8

	st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
	st->codec->codec_id = CODEC_ID_RAWVIDEO;
	st->codec->width = avs->vi->width;
	st->codec->height = avs->vi->height;

	st->time_base = (AVRational) {avs->vi->fps_denominator, avs->vi->fps_numerator};
	st->avg_frame_rate = (AVRational) {avs->vi->fps_numerator, avs->vi->fps_denominator};
	st->start_time = 0;
	st->duration = avs->vi->num_frames;
	st->nb_frames = avs->vi->num_frames;

	switch (avs->vi->pixel_type) {
	#ifdef _WIN32
	case AVS_CS_YV24:
	st->codec->pix_fmt = AV_PIX_FMT_YUV444P;
	planar = 1;
	break;
	case AVS_CS_YV16:
	st->codec->pix_fmt = AV_PIX_FMT_YUV422P;
	planar = 1;
	break;
	case AVS_CS_YV411:
	st->codec->pix_fmt = AV_PIX_FMT_YUV411P;
	planar = 1;
	break;
	case AVS_CS_Y8:
	st->codec->pix_fmt = AV_PIX_FMT_GRAY8;
	planar = 2;
	break;
	#endif
	case AVS_CS_BGR24:
	st->codec->pix_fmt = AV_PIX_FMT_BGR24;
	break;
	case AVS_CS_BGR32:
	st->codec->pix_fmt = AV_PIX_FMT_RGB32;
	break;
	case AVS_CS_YUY2:
	st->codec->pix_fmt = AV_PIX_FMT_YUYV422;
	break;
	case AVS_CS_YV12:
	st->codec->pix_fmt = AV_PIX_FMT_YUV420P;
	planar = 1;
	break;
	case AVS_CS_I420: // Is this even used anywhere?
	st->codec->pix_fmt = AV_PIX_FMT_YUV420P;
	planar = 1;
	break;
	default:
	av_log(s, AV_LOG_ERROR, "unknown AviSynth colorspace %d\n", avs->vi->pixel_type);
	avs->error = 1;
	return AVERROR_UNKNOWN;
	}

	switch (planar) {
	case 2: // Y8
	avs->n_planes = 1;
	avs->planes = avs_planes_grey;
	break;
	case 1: // YUV
	avs->n_planes = 3;
	avs->planes = avs_planes_yuv;
	break;
	default:
	avs->n_planes = 1;
	avs->planes = avs_planes_packed;
	}
	return 0;
	}

	static int avisynth_create_stream_audio(AVFormatContext s, AVStream st) {
	AviSynthContext *avs = s->priv_data;

	st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
	st->codec->sample_rate = avs->vi->audio_samples_per_second;
	st->codec->channels = avs->vi->nchannels;
	st->time_base = (AVRational) {1, avs->vi->audio_samples_per_second};

	switch (avs->vi->sample_type) {
	case AVS_SAMPLE_INT8:
	st->codec->codec_id = CODEC_ID_PCM_U8;
	break;
	case AVS_SAMPLE_INT16:
	st->codec->codec_id = CODEC_ID_PCM_S16LE;
	break;
	case AVS_SAMPLE_INT24:
	st->codec->codec_id = CODEC_ID_PCM_S24LE;
	break;
	case AVS_SAMPLE_INT32:
	st->codec->codec_id = CODEC_ID_PCM_S32LE;
	break;
	case AVS_SAMPLE_FLOAT:
	st->codec->codec_id = CODEC_ID_PCM_F32LE;
	break;
	default:
	av_log(s, AV_LOG_ERROR, "unknown AviSynth sample type %d\n", avs->vi->sample_type);
	avs->error = 1;
	return AVERROR_UNKNOWN;
	}
	return 0;
	}

	static int avisynth_create_stream(AVFormatContext *s) {
	AviSynthContext *avs = s->priv_data;
	AVStream *st;
	int ret;
	int id = 0;

	if (avs_has_video(avs->vi)) {
	st = avformat_new_stream(s, NULL);
	if (!st)
	return AVERROR_UNKNOWN;
	st->id = id++;
	if (ret = avisynth_create_stream_video(s, st))
	return ret;
	}
	if (avs_has_audio(avs->vi)) {
	st = avformat_new_stream(s, NULL);
	if (!st)
	return AVERROR_UNKNOWN;
	st->id = id++;
	if (ret = avisynth_create_stream_audio(s, st))
	return ret;
	}
	return 0;
	}

	static int avisynth_open_file(AVFormatContext *s) {
	AviSynthContext avs = (AviSynthContext )s->priv_data;
	AVS_Value arg, val;
	int ret;
	#ifdef _WIN32
	char filename_ansi[MAX_PATH * 4];
	wchar_t filename_wc[MAX_PATH * 4];
	#endif

	if (ret = avisynth_context_create(s))
	return ret;

	#ifdef _WIN32
	// Convert UTF-8 to ANSI code page
	MultiByteToWideChar(CP_UTF8, 0, s->filename, -1, filename_wc, MAX_PATH * 4);
	WideCharToMultiByte(CP_THREAD_ACP, 0, filename_wc, -1, filename_ansi, MAX_PATH * 4, NULL, NULL);
	arg = avs_new_value_string(filename_ansi);
	#else
	arg = avs_new_value_string(s->filename);
	#endif
	val = avs_library->avs_invoke(avs->env, "Import", arg, 0);
	if (avs_is_error(val)) {
	av_log(s, AV_LOG_ERROR, "%s\n", avs_as_error(val));
	ret = AVERROR_UNKNOWN;
	goto fail;
	}
	if (!avs_is_clip(val)) {
	av_log(s, AV_LOG_ERROR, "%s\n", "AviSynth script did not return a clip");
	ret = AVERROR_UNKNOWN;
	goto fail;
	}

	avs->clip = avs_library->avs_take_clip(val, avs->env);
	avs->vi = avs_library->avs_get_video_info(avs->clip);

	// Release the AVS_Value as it will go out of scope.
	avs_library->avs_release_value(val);

	if (ret = avisynth_create_stream(s))
	goto fail;

	return 0;

	fail:
	avisynth_context_destroy(avs);
	return ret;
	}

	static void avisynth_next_stream(AVFormatContext s, AVStream st, AVPacket pkt, int *discard) {
	AviSynthContext *avs = s->priv_data;

	pkt->stream_index = avs->curr_stream++;
	avs->curr_stream %= s->nb_streams;

	*st = s->streams[pkt->stream_index];
	if ((*st)->discard == AVDISCARD_ALL)
	*discard = 1;
	else
	*discard = 0;

	return;
	}

	// Copy AviSynth clip data into an AVPacket.
	static int avisynth_read_packet_video(AVFormatContext s, AVPacket pkt, int discard) {
	AviSynthContext *avs = s->priv_data;
	AVS_VideoFrame *frame;
	unsigned char *dst_p;
	const unsigned char *src_p;
	int n, i, plane, rowsize, planeheight, pitch, bits;
	const char *error;

	if (avs->curr_frame >= avs->vi->num_frames)
	return AVERROR_EOF;

	// This must happen even if the stream is discarded to prevent desync.
	n = avs->curr_frame++;
	if (discard)
	return 0;

	pkt->pts = n;
	pkt->dts = n;
	pkt->duration = 1;

	// Define the bpp values for the new AviSynth 2.6 colorspaces
	if (avs_is_yv24(avs->vi)) {
	bits = 24;
	} else if (avs_is_yv16(avs->vi)) {
	bits = 16;
	} else if (avs_is_yv411(avs->vi)) {
	bits = 12;
	} else if (avs_is_y8(avs->vi)) {
	bits = 8;
	} else {
	bits = avs_bits_per_pixel(avs->vi);
	}

	// Without cast to int64_t, calculation overflows at about 9k x 9k resolution.
	pkt->size = (((int64_t)avs->vi->width * (int64_t)avs->vi->height) * bits) / 8;
	if (!pkt->size)
	return AVERROR_UNKNOWN;
	pkt->data = av_malloc(pkt->size);
	if (!pkt->data)
	return AVERROR_UNKNOWN;

	frame = avs_library->avs_get_frame(avs->clip, n);
	error = avs_library->avs_clip_get_error(avs->clip);
	if (error) {
	av_log(s, AV_LOG_ERROR, "%s\n", error);
	avs->error = 1;
	av_freep(&pkt->data);
	return AVERROR_UNKNOWN;
	}

	dst_p = pkt->data;
	for (i = 0; i < avs->n_planes; i++) {
	plane = avs->planes[i];
	src_p = avs_get_read_ptr_p(frame, plane);
	pitch = avs_get_pitch_p(frame, plane);

	#ifdef _WIN32
	if (avs_library->avs_get_version(avs->clip) == 3) {
	rowsize = avs_get_row_size_p_25(frame, plane);
	planeheight = avs_get_height_p_25(frame, plane);
	} else {
	rowsize = avs_get_row_size_p(frame, plane);
	planeheight = avs_get_height_p(frame, plane);
	}
	#else
	rowsize = avs_get_row_size_p(frame, plane);
	planeheight = avs_get_height_p(frame, plane);
	#endif

	// Flip RGB video.
	if (avs_is_rgb24(avs->vi) \|\| avs_is_rgb(avs->vi)) {
	src_p = src_p + (planeheight - 1) * pitch;
	pitch = -pitch;
	}

	avs_library->avs_bit_blt(avs->env, dst_p, rowsize, src_p, pitch, rowsize, planeheight);
	dst_p += rowsize * planeheight;
	}

	avs_library->avs_release_video_frame(frame);
	return 0;
	}

	static int avisynth_read_packet_audio(AVFormatContext s, AVPacket pkt, int discard) {
	AviSynthContext *avs = s->priv_data;
	AVRational fps, samplerate;
	int samples;
	int64_t n;
	const char *error;

	if (avs->curr_sample >= avs->vi->num_audio_samples)
	return AVERROR_EOF;

	fps.num = avs->vi->fps_numerator;
	fps.den = avs->vi->fps_denominator;
	samplerate.num = avs->vi->audio_samples_per_second;
	samplerate.den = 1;

	if (avs_has_video(avs->vi)) {
	if (avs->curr_frame < avs->vi->num_frames)
	samples = av_rescale_q(avs->curr_frame, samplerate, fps) - avs->curr_sample;
	else
	samples = av_rescale_q(1, samplerate, fps);
	} else {
	samples = 1000;
	}

	// After seeking, audio may catch up with video.
	if (samples <= 0) {
	pkt->size = 0;
	pkt->data = NULL;
	return 0;
	}

	if (avs->curr_sample + samples > avs->vi->num_audio_samples)
	samples = avs->vi->num_audio_samples - avs->curr_sample;

	// This must happen even if the stream is discarded to prevent desync.
	n = avs->curr_sample;
	avs->curr_sample += samples;
	if (discard)
	return 0;

	pkt->pts = n;
	pkt->dts = n;
	pkt->duration = samples;

	pkt->size = avs_bytes_per_channel_sample(avs->vi) * samples * avs->vi->nchannels;
	if (!pkt->size)
	return AVERROR_UNKNOWN;
	pkt->data = av_malloc(pkt->size);
	if (!pkt->data)
	return AVERROR_UNKNOWN;

	avs_library->avs_get_audio(avs->clip, pkt->data, n, samples);
	error = avs_library->avs_clip_get_error(avs->clip);
	if (error) {
	av_log(s, AV_LOG_ERROR, "%s\n", error);
	avs->error = 1;
	av_freep(&pkt->data);
	return AVERROR_UNKNOWN;
	}
	return 0;
	}

	static av_cold int avisynth_read_header(AVFormatContext *s) {
	int ret;

	// Calling library must implement a lock for thread-safe opens.
	if (ret = avpriv_lock_avformat())
	return ret;

	if (ret = avisynth_open_file(s)) {
	avpriv_unlock_avformat();
	return ret;
	}

	avpriv_unlock_avformat();
	return 0;
	}

	static int avisynth_read_packet(AVFormatContext s, AVPacket pkt) {
	AviSynthContext *avs = s->priv_data;
	AVStream *st;
	int discard = 0;
	int ret;

	if (avs->error)
	return AVERROR_UNKNOWN;

	pkt->destruct = av_destruct_packet;

	// If either stream reaches EOF, try to read the other one before giving up.
	avisynth_next_stream(s, &st, pkt, &discard);
	if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
	ret = avisynth_read_packet_video(s, pkt, discard);
	if (ret == AVERROR_EOF && avs_has_audio(avs->vi)) {
	avisynth_next_stream(s, &st, pkt, &discard);
	return avisynth_read_packet_audio(s, pkt, discard);
	}
	return ret;
	} else {
	ret = avisynth_read_packet_audio(s, pkt, discard);
	if (ret == AVERROR_EOF && avs_has_video(avs->vi)) {
	avisynth_next_stream(s, &st, pkt, &discard);
	return avisynth_read_packet_video(s, pkt, discard);
	}
	return ret;
	}
	}

	static av_cold int avisynth_read_close(AVFormatContext *s) {
	if (avpriv_lock_avformat())
	return AVERROR_UNKNOWN;

	avisynth_context_destroy(s->priv_data);
	avpriv_unlock_avformat();
	return 0;
	}

	static int avisynth_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
	AviSynthContext *avs = s->priv_data;
	AVStream *st;
	AVRational fps, samplerate;

	if (avs->error)
	return AVERROR_UNKNOWN;

	fps = (AVRational) {avs->vi->fps_numerator, avs->vi->fps_denominator};
	samplerate = (AVRational) {avs->vi->audio_samples_per_second, 1};

	st = s->streams[stream_index];
	if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
	// AviSynth frame counts are signed int.
	if ((timestamp >= avs->vi->num_frames) \|\| (timestamp > INT_MAX) \|\| (timestamp < 0))
	return AVERROR_EOF;
	avs->curr_frame = timestamp;
	if (avs_has_audio(avs->vi))
	avs->curr_sample = av_rescale_q(timestamp, samplerate, fps);
	} else {
	if ((timestamp >= avs->vi->num_audio_samples) \|\| (timestamp < 0))
	return AVERROR_EOF;
	// Force frame granularity for seeking.
	if (avs_has_video(avs->vi)) {
	avs->curr_frame = av_rescale_q(timestamp, fps, samplerate);
	avs->curr_sample = av_rescale_q(avs->curr_frame, samplerate, fps);
	} else {
	avs->curr_sample = timestamp;
	}
	}

	return 0;
	}

	AVInputFormat ff_avisynth_demuxer = {
	.name = "avisynth",
	.long_name = NULL_IF_CONFIG_SMALL("AviSynth script"),
	.priv_data_size = sizeof(AviSynthContext),
	.read_header = avisynth_read_header,
	.read_packet = avisynth_read_packet,
	.read_close = avisynth_read_close,
	.read_seek = avisynth_read_seek,
	.extensions = "avs",
	};