/*

  * AviSynth/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 "libavutil/attributes.h"

 #include "libavutil/internal.h"

 #include "libavcodec/internal.h"

 #include "avformat.h"

 #include "internal.h"

 #include "config.h"

 /* Enable function pointer definitions for runtime loading. */

 #define AVSC_NO_DECLSPEC
 

 /* Platform-specific directives for AviSynth vs AvxSynth. */

 #ifdef _WIN32

   #include "compat/w32dlfcn.h"

   #undef EXTERN_C
   #include "compat/avisynth/avisynth_c.h"
   #define AVISYNTH_LIB "avisynth"

   #define USING_AVISYNTH

 #else
   #include <dlfcn.h>
   #include "compat/avisynth/avxsynth_c.h"

   #define AVISYNTH_NAME "libavxsynth"
   #define AVISYNTH_LIB AVISYNTH_NAME SLIBSUF

 #endif

 typedef struct AviSynthLibrary {

     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);

 #ifdef USING_AVISYNTH
     AVSC_DECLARE_FUNC(avs_bits_per_pixel);
     AVSC_DECLARE_FUNC(avs_get_height_p);
     AVSC_DECLARE_FUNC(avs_get_pitch_p);
     AVSC_DECLARE_FUNC(avs_get_read_ptr_p);
     AVSC_DECLARE_FUNC(avs_get_row_size_p);

     AVSC_DECLARE_FUNC(avs_is_planar_rgb);
     AVSC_DECLARE_FUNC(avs_is_planar_rgba);

 #endif

 #undef AVSC_DECLARE_FUNC
 } AviSynthLibrary;
 

 typedef 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;

 } 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 };

 #ifdef USING_AVISYNTH
 static const int avs_planes_rgb[3]    = { AVS_PLANAR_G, AVS_PLANAR_B,
                                           AVS_PLANAR_R };
 static const int avs_planes_yuva[4]   = { AVS_PLANAR_Y, AVS_PLANAR_U,
                                           AVS_PLANAR_V, AVS_PLANAR_A };
 static const int avs_planes_rgba[4]   = { AVS_PLANAR_G, AVS_PLANAR_B,
                                           AVS_PLANAR_R, AVS_PLANAR_A };
 #endif

 /* 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;

 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.library = dlopen(AVISYNTH_LIB, RTLD_NOW | RTLD_LOCAL);

     if (!avs_library.library)

         return AVERROR_UNKNOWN;
 

 #define LOAD_AVS_FUNC(name, continue_on_fail)                          \

         avs_library.name = dlsym(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);

 #ifdef USING_AVISYNTH

     LOAD_AVS_FUNC(avs_bits_per_pixel, 1);
     LOAD_AVS_FUNC(avs_get_height_p, 1);
     LOAD_AVS_FUNC(avs_get_pitch_p, 1);
     LOAD_AVS_FUNC(avs_get_read_ptr_p, 1);
     LOAD_AVS_FUNC(avs_get_row_size_p, 1);

     LOAD_AVS_FUNC(avs_is_planar_rgb, 1);
     LOAD_AVS_FUNC(avs_is_planar_rgba, 1);

 #endif

 #undef LOAD_AVS_FUNC
 
     atexit(avisynth_atexit_handler);
     return 0;
 
 fail:

     dlclose(avs_library.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 = s->priv_data;

     int ret;
 

     if (!avs_library.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;
     }

     dlclose(avs_library.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, 3: Planar RGB, 4: YUVA, 5: Planar RGBA

     st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
     st->codecpar->codec_id   = AV_CODEC_ID_RAWVIDEO;
     st->codecpar->width      = avs->vi->width;
     st->codecpar->height     = avs->vi->height;

 
     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;

     avpriv_set_pts_info(st, 32, avs->vi->fps_denominator, avs->vi->fps_numerator);

 
     switch (avs->vi->pixel_type) {

 #ifdef USING_AVISYNTH

     /* 10~16-bit YUV pix_fmts (AviSynth+) */

     case AVS_CS_YUV444P10:
         st->codecpar->format = AV_PIX_FMT_YUV444P10;
         planar               = 1;
         break;
     case AVS_CS_YUV422P10:
         st->codecpar->format = AV_PIX_FMT_YUV422P10;
         planar               = 1;
         break;
     case AVS_CS_YUV420P10:
         st->codecpar->format = AV_PIX_FMT_YUV420P10;
         planar               = 1;
         break;
     case AVS_CS_YUV444P12:
         st->codecpar->format = AV_PIX_FMT_YUV444P12;
         planar               = 1;
         break;
     case AVS_CS_YUV422P12:
         st->codecpar->format = AV_PIX_FMT_YUV422P12;
         planar               = 1;
         break;
     case AVS_CS_YUV420P12:
         st->codecpar->format = AV_PIX_FMT_YUV420P12;
         planar               = 1;
         break;
     case AVS_CS_YUV444P14:
         st->codecpar->format = AV_PIX_FMT_YUV444P14;
         planar               = 1;
         break;
     case AVS_CS_YUV422P14:
         st->codecpar->format = AV_PIX_FMT_YUV422P14;
         planar               = 1;
         break;
     case AVS_CS_YUV420P14:
         st->codecpar->format = AV_PIX_FMT_YUV420P14;
         planar               = 1;
         break;
     case AVS_CS_YUV444P16:
         st->codecpar->format = AV_PIX_FMT_YUV444P16;
         planar               = 1;
         break;
     case AVS_CS_YUV422P16:
         st->codecpar->format = AV_PIX_FMT_YUV422P16;
         planar               = 1;
         break;
     case AVS_CS_YUV420P16:
         st->codecpar->format = AV_PIX_FMT_YUV420P16;
         planar               = 1;
         break;

     /* 8~16-bit YUV pix_fmts with Alpha (AviSynth+) */

     case AVS_CS_YUVA444:
         st->codecpar->format = AV_PIX_FMT_YUVA444P;
         planar               = 4;
         break;
     case AVS_CS_YUVA422:
         st->codecpar->format = AV_PIX_FMT_YUVA422P;
         planar               = 4;
         break;
     case AVS_CS_YUVA420:
         st->codecpar->format = AV_PIX_FMT_YUVA420P;
         planar               = 4;
         break;
     case AVS_CS_YUVA444P10:
         st->codecpar->format = AV_PIX_FMT_YUVA444P10;
         planar               = 4;
         break;
     case AVS_CS_YUVA422P10:
         st->codecpar->format = AV_PIX_FMT_YUVA422P10;
         planar               = 4;
         break;
     case AVS_CS_YUVA420P10:
         st->codecpar->format = AV_PIX_FMT_YUVA420P10;
         planar               = 4;
         break;
     case AVS_CS_YUVA444P16:
         st->codecpar->format = AV_PIX_FMT_YUVA444P16;
         planar               = 4;
         break;
     case AVS_CS_YUVA422P16:
         st->codecpar->format = AV_PIX_FMT_YUVA422P16;
         planar               = 4;
         break;
     case AVS_CS_YUVA420P16:
         st->codecpar->format = AV_PIX_FMT_YUVA420P16;
         planar               = 4;
         break;

     /* Planar RGB pix_fmts (AviSynth+) */

     case AVS_CS_RGBP:
         st->codecpar->format = AV_PIX_FMT_GBRP;
         planar               = 3;
         break;
     case AVS_CS_RGBP10:
         st->codecpar->format = AV_PIX_FMT_GBRP10;
         planar               = 3;
         break;
     case AVS_CS_RGBP12:
         st->codecpar->format = AV_PIX_FMT_GBRP12;
         planar               = 3;
         break;
     case AVS_CS_RGBP14:
         st->codecpar->format = AV_PIX_FMT_GBRP14;
         planar               = 3;
         break;
     case AVS_CS_RGBP16:
         st->codecpar->format = AV_PIX_FMT_GBRP16;
         planar               = 3;
         break;

     /* Planar RGB pix_fmts with Alpha (AviSynth+) */

     case AVS_CS_RGBAP:
         st->codecpar->format = AV_PIX_FMT_GBRAP;
         planar               = 5;
         break;
     case AVS_CS_RGBAP10:
         st->codecpar->format = AV_PIX_FMT_GBRAP10;
         planar               = 5;
         break;
     case AVS_CS_RGBAP12:
         st->codecpar->format = AV_PIX_FMT_GBRAP12;
         planar               = 5;
         break;
     case AVS_CS_RGBAP16:
         st->codecpar->format = AV_PIX_FMT_GBRAP16;
         planar               = 5;
         break;

     /* GRAY16 (AviSynth+) */

     case AVS_CS_Y16:
         st->codecpar->format = AV_PIX_FMT_GRAY16;
         planar               = 2;
         break;

     /* pix_fmts added in AviSynth 2.6 */

     case AVS_CS_YV24:

         st->codecpar->format = AV_PIX_FMT_YUV444P;
         planar               = 1;

         break;
     case AVS_CS_YV16:

         st->codecpar->format = AV_PIX_FMT_YUV422P;
         planar               = 1;

         break;
     case AVS_CS_YV411:

         st->codecpar->format = AV_PIX_FMT_YUV411P;
         planar               = 1;

         break;
     case AVS_CS_Y8:

         st->codecpar->format = AV_PIX_FMT_GRAY8;
         planar               = 2;

         break;

     /* 16-bit packed RGB pix_fmts (AviSynth+) */

     case AVS_CS_BGR48:
         st->codecpar->format = AV_PIX_FMT_BGR48;
         break;
     case AVS_CS_BGR64:
         st->codecpar->format = AV_PIX_FMT_BGRA64;
         break;

 #endif

     /* AviSynth 2.5 and AvxSynth pix_fmts */

     case AVS_CS_BGR24:

         st->codecpar->format = AV_PIX_FMT_BGR24;

         break;
     case AVS_CS_BGR32:

         st->codecpar->format = AV_PIX_FMT_RGB32;

         break;
     case AVS_CS_YUY2:

         st->codecpar->format = AV_PIX_FMT_YUYV422;

         break;
     case AVS_CS_YV12:

         st->codecpar->format = AV_PIX_FMT_YUV420P;
         planar               = 1;

         break;
     case AVS_CS_I420: // Is this even used anywhere?

         st->codecpar->format = 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) {

 #ifdef USING_AVISYNTH
     case 5: // Planar RGB + Alpha
         avs->n_planes = 4;
         avs->planes   = avs_planes_rgba;
         break;
     case 4: // YUV + Alpha
         avs->n_planes = 4;
         avs->planes   = avs_planes_yuva;
         break;
     case 3: // Planar RGB
         avs->n_planes = 3;
         avs->planes   = avs_planes_rgb;
         break;
 #endif

     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->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
     st->codecpar->sample_rate = avs->vi->audio_samples_per_second;
     st->codecpar->channels    = avs->vi->nchannels;

     st->duration              = avs->vi->num_audio_samples;

     avpriv_set_pts_info(st, 64, 1, avs->vi->audio_samples_per_second);

 
     switch (avs->vi->sample_type) {
     case AVS_SAMPLE_INT8:

         st->codecpar->codec_id = AV_CODEC_ID_PCM_U8;

         break;
     case AVS_SAMPLE_INT16:

         st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;

         break;
     case AVS_SAMPLE_INT24:

         st->codecpar->codec_id = AV_CODEC_ID_PCM_S24LE;

         break;
     case AVS_SAMPLE_INT32:

         st->codecpar->codec_id = AV_CODEC_ID_PCM_S32LE;

         break;
     case AVS_SAMPLE_FLOAT:

         st->codecpar->codec_id = AV_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 = s->priv_data;

     AVS_Value arg, val;
     int ret;

 #ifdef USING_AVISYNTH

     char filename_ansi[MAX_PATH * 4];
     wchar_t filename_wc[MAX_PATH * 4];
 #endif

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

 #ifdef USING_AVISYNTH

     /* 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, "AviSynth script did not return a clip\n");

         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);

 #ifdef USING_AVISYNTH

     /* On Windows, FFmpeg supports AviSynth interface version 6 or higher.
      * This includes AviSynth 2.6 RC1 or higher, and AviSynth+ r1718 or higher,
      * and excludes 2.5 and the 2.6 alphas. Since AvxSynth identifies itself
      * as interface version 3 like 2.5.8, this needs to be special-cased. */

     if (avs_library.avs_get_version(avs->clip) < 6) {

         av_log(s, AV_LOG_ERROR,

                "AviSynth version is too old. Please upgrade to either AviSynth 2.6 >= RC1 or AviSynth+ >= r1718.\n");

         ret = AVERROR_UNKNOWN;
         goto fail;
     }
 #endif
 

     /* 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;

     avs->curr_stream++;

     avs->curr_stream %= s->nb_streams;
 

     *st = s->streams[avs->curr_stream];

     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;

     int avsplus av_unused;

 
     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;
 

 #ifdef USING_AVISYNTH

     /* Detect whether we're using AviSynth 2.6 or AviSynth+ by
      * looking for whether avs_is_planar_rgb exists. */
     if (GetProcAddress(avs_library.library, "avs_is_planar_rgb") == NULL)
         avsplus = 0;
     else
         avsplus = 1;
 

     /* avs_bits_per_pixel changed to AVSC_API with AviSynth 2.6, which
      * requires going through avs_library, while AvxSynth has it under
      * the older AVSC_INLINE type, so special-case this. */
 
     bits = avs_library.avs_bits_per_pixel(avs->vi);

 #else
     bits = avs_bits_per_pixel(avs->vi);

 #endif

     /* Without the 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;

     if (av_new_packet(pkt, pkt->size) < 0)

         return AVERROR(ENOMEM);

     pkt->pts      = n;
     pkt->dts      = n;
     pkt->duration = 1;
     pkt->stream_index = avs->curr_stream;

     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_packet_unref(pkt);

         return AVERROR_UNKNOWN;
     }
 
     dst_p = pkt->data;
     for (i = 0; i < avs->n_planes; i++) {
         plane = avs->planes[i];

 #ifdef USING_AVISYNTH

         src_p = avs_library.avs_get_read_ptr_p(frame, plane);
         pitch = avs_library.avs_get_pitch_p(frame, plane);
 

         rowsize     = avs_library.avs_get_row_size_p(frame, plane);
         planeheight = avs_library.avs_get_height_p(frame, plane);

 #else

         src_p = avs_get_read_ptr_p(frame, plane);
         pitch = avs_get_pitch_p(frame, plane);
 

         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;
         }
 

 #ifdef USING_AVISYNTH

         /* Flip Planar RGB video */

         if (avsplus && (avs_library.avs_is_planar_rgb(avs->vi) ||

                         avs_library.avs_is_planar_rgba(avs->vi))) {
             src_p = src_p + (planeheight - 1) * pitch;

             pitch = -pitch;

         }

 #endif
 

         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->size = avs_bytes_per_channel_sample(avs->vi) *
                 samples * avs->vi->nchannels;

     if (!pkt->size)
         return AVERROR_UNKNOWN;

     if (av_new_packet(pkt, pkt->size) < 0)

         return AVERROR(ENOMEM);

     pkt->pts      = n;
     pkt->dts      = n;
     pkt->duration = samples;
     pkt->stream_index = avs->curr_stream;

     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_packet_unref(pkt);

         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 = ff_lock_avformat())

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

         ff_unlock_avformat();

         return ret;
     }
 

     ff_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;
 

     /* If either stream reaches EOF, try to read the other one before
      * giving up. */

     avisynth_next_stream(s, &st, pkt, &discard);

     if (st->codecpar->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);
         }
     } 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 (ff_lock_avformat())

         return AVERROR_UNKNOWN;
 
     avisynth_context_destroy(s->priv_data);

     ff_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->codecpar->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",

 };