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• libavcodec avcodec_open2 returns -22

  28 juillet 2012, par buchtak

  I am trying to learn how to encode video using libavcodec library. I use the following initialization :

  avcodec_register_all();
  
  
  
  // This works fine.
  
  AVCodec *avcodec = avcodec_find_encoder( CODEC_ID_H264 );
  
  
  
  AVCodecContext *avctx = avcodec_alloc_context3( avcodec );
  
  avctx->bit_rate      = 400000;
  
  avctx->width         = 640;
  
  avctx->height        = 480;
  
  avctx->time_base.den = 15;
  
  avctx->time_base.num = 1;
  
  avctx->gop_size      = 10;
  
  avctx->max_b_frames  = 1;
  
  avctx->pix_fmt       = PIX_FMT_YUV420P;
  
  av_opt_set( avctx->priv_data, "preset", "slow", 0 );
  
  
  
  // ret should be zero, but it's negative
  
  int ret = avcodec_open2( avctx, avcodec, NULL );

  However, avcodec_open2(...) always returns a negative value. The avcodec_find_encoder(...) works fine and the returned pointer is not NULL. I use Win7 x64, 64-bit Zeranoe FFmpeg build from

  http://ffmpeg.zeranoe.com/builds/

  According to the readme the FFmpeg version is 2012-06-22 git-c17808c built with --enable-libx264. I also tried CODEC_ID_MPEG1VIDEO and changing some of the initialization parameters, but no matter what I do, the avcodec_open2(...) always returns value -22. The decoding/encoding example provided with the Zeranoe build (it's the same one as http://ffmpeg.org/doxygen/trunk/api-example_8c-source.html) does not work either...

• Understanding FFMPEG Video Encoding

  20 juin 2014, par SetSlapShot

  Got this from the encoding example in ffmpeg. I can somewhat follow the authors example for audio encoding, but I find myself befuddled looking at the C code (I commented in block numbers to help me reference what I’m talking about)...

  static void video_encode_example(const char *filename)
  
  {
  
  AVCodec *codec;
  
  AVCodecContext *c= NULL;
  
  int i, out_size, size, x, y, outbuf_size;
  
  FILE *f;
  
  AVFrame *picture;
  
  uint8_t *outbuf, *picture_buf;              //BLOCK ONE
  
  printf("Video encoding\n");
  
  
  
  /* find the mpeg1 video encoder */
  
  codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
  
  if (!codec) {
  
      fprintf(stderr, "codec not found\n");
  
      exit(1);                                //BLOCK TWO
  
  }
  
  
  
  c= avcodec_alloc_context();
  
  picture= avcodec_alloc_frame();
  
  /* put sample parameters */
  
  c->bit_rate = 400000;
  
  /* resolution must be a multiple of two */
  
  c->width = 352;
  
  c->height = 288;
  
  /* frames per second */
  
  c->time_base= (AVRational){1,25};
  
  c->gop_size = 10; /* emit one intra frame every ten frames */
  
  c->max_b_frames=1;
  
  c->pix_fmt = PIX_FMT_YUV420P;                   //BLOCK THREE
  
  
  
  /* open it */
  
  if (avcodec_open(c, codec) < 0) {
  
      fprintf(stderr, "could not open codec\n");
  
      exit(1);
  
  }
  
  f = fopen(filename, "wb");
  
  if (!f) {
  
      fprintf(stderr, "could not open %s\n", filename);
  
      exit(1);
  
  }                                               //BLOCK FOUR
  
  
  
  /* alloc image and output buffer */
  
  outbuf_size = 100000;
  
  outbuf = malloc(outbuf_size);
  
  size = c->width * c->height;
  
  picture_buf = malloc((size * 3) / 2); /* size for YUV 420 */
  
  picture->data[0] = picture_buf;
  
  picture->data[1] = picture->data[0] + size;
  
  picture->data[2] = picture->data[1] + size / 4;
  
  picture->linesize[0] = c->width;
  
  picture->linesize[1] = c->width / 2;
  
  picture->linesize[2] = c->width / 2;              //BLOCK FIVE
  
  
  
  /* encode 1 second of video */
  
  for(i=0;i<25;i++) {
  
      fflush(stdout);
  
      /* prepare a dummy image */
  
      /* Y */
  
      for(y=0;yheight;y++) {
  
          for(x=0;xwidth;x++) {
  
              picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
  
          }
  
      }                                            //BLOCK SIX
  
  
  
      /* Cb and Cr */
  
      for(y=0;yheight/2;y++) {
  
          for(x=0;xwidth/2;x++) {
  
              picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
  
              picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
  
          }
  
      }                                           //BLOCK SEVEN
  
  
  
      /* encode the image */
  
      out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
  
      printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
      fwrite(outbuf, 1, out_size, f);
  
  }                                              //BLOCK EIGHT
  
  
  
  /* get the delayed frames */
  
  for(; out_size; i++) {
  
      fflush(stdout);
  
      out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
  
      printf("write frame %3d (size=%5d)\n", i, out_size);
  
      fwrite(outbuf, 1, out_size, f);
  
  }                                             //BLOCK NINE
  
  
  
  /* add sequence end code to have a real mpeg file */
  
  outbuf[0] = 0x00;
  
  outbuf[1] = 0x00;
  
  outbuf[2] = 0x01;
  
  outbuf[3] = 0xb7;
  
  fwrite(outbuf, 1, 4, f);
  
  fclose(f);
  
  free(picture_buf);
  
  free(outbuf);
  
  avcodec_close(c);
  
  av_free(c);
  
  av_free(picture);
  
  }                                            //BLOCK TEN

  Here’s what I can get from the authors code block by block...

  BLOCK ONE : Initializing Variables and pointers. I couldn’t find the AVFrame struct yet in the ffmpeg source code so I don’t know what its referencing

  BLOCK TWO : Uses a codec from the file, if not found close.

  BLOCK THREE : Sets sample video parameters. Only thing I don’t really get is gop size. I read about intra frames and I still don’t get what they are.

  BLOCK FOUR : Open the file for writing...

  BLOCK FIVE : Here’s where they really start losing me. Part is probably because I don’t know exactly what AVFrame is, but why do they only use 3/2 of the image size ?

  BLOCK SIX & SEVEN : I don’t understand what they are trying to accomplish with this math.

  BLOCK EIGHT : It looks like the avcodec function does all the work here, not concerned with that for the time being..

  BLOCK NINE : Since it’s outside the 25 frame for loop I assume it gets the leftover frames ?

  BLOCK TEN : Close, free mem, etc...

  I know this is a large block of code to be confused with, any input would be helpful. I got put in over my head at work. Thanks in advance SO.

• ffmpeg encoded hls makes audio and video progressively out of sync

  21 septembre 2020, par eschie

  When trying to encoding a source .mp4 to multiple bitrates and sizes for adaptive HLSv3 playback the resulting audio and video become progressively out of sync. When scrubbing to a later point it seems to reset, and stay in sync.

  



  I'm on the latest ffmpeg 4.2.1 via homebrew-ffmpeg, with the libfdk-aac codec. Note, this was also occurring with ffmpeg 4.1.

  



  ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.1-with-options_1 --enable-shared --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libaom --enable-libmp3lame --enable-libopus --enable-libsnappy --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --disable-libjack --disable-indev=jack --enable-opencl --enable-videotoolbox --disable-htmlpages --enable-libfdk-aac --enable-nonfree
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100


  



  The audio and video streams are marginally off, would that cause this problem ?

  



  ffprobe -v error -select_streams v:0 -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 INPUT_FILE.mp4
80.480400

  



  ffprobe -v error -select_streams a:0 -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 INPUT_FILE.mp4
80.469333

  



  Here is some metadata on the source file :

  



  General
Complete name                            : INPUT_VIDEO.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (mp42/mp41)
File size                                : 236 MiB
Duration                                 : 1 min 21 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 24.2 Mb/s
Encoded date                             : UTC 2019-08-27 22:13:53
Tagged date                              : UTC 2019-08-27 22:15:15
TIM                                      : 00;00;00;00
TSC                                      : 30000
TSZ                                      : 1001

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Main@L4.1
Format settings                          : CABAC / 2 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 2 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 1 min 21 s
Bit rate mode                            : Variable
Bit rate                                 : 23.8 Mb/s
Maximum bit rate                         : 768 kb/s
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (30000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.383
Stream size                              : 233 MiB (99%)
Language                                 : English
Encoded date                             : UTC 2019-08-27 22:13:53
Tagged date                              : UTC 2019-08-27 22:13:53
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 1 min 21 s
Source duration                          : 1 min 21 s
Bit rate mode                            : Constant
Bit rate                                 : 317 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 3.10 MiB (1%)
Source stream size                       : 3.10 MiB (1%)
Language                                 : English
Encoded date                             : UTC 2019-08-27 22:13:53
Tagged date                              : UTC 2019-08-27 22:13:53


  



  And the encoding command :

  



  ffmpeg \
-i INPUT_VIDEO \
-dn \
-sn \
-filter_complex \
"[0:v]fps=fps=24000/1001, \
setpts=(PTS-STARTPTS), \
split=12[vsplit1][vsplit2][vsplit3][vsplit4][vsplit5][vsplit6][vsplit7][vsplit8][vsplit9][vsplit10][vsplit11][vsplit12]; \
[vsplit1]scale=-1:1080[video_1080_4.1]; \
[vsplit2]scale=-1:720[video_720_4.1]; \
[vsplit3]scale=-1:720[video_720_3.1]; \
[vsplit4]scale=-1:540[video_540_3.1]; \
[vsplit5]scale=-1:432[video_432_3.1]; \
[vsplit6]scale=-1:270[video_270_3.0]; \
[vsplit7]scale=-1:270[video_270_3.1]; \
[vsplit8]scale=-1:144[video_144_4.1]; \
[vsplit9]scale=-1:144[video_144_3.0]; \
[vsplit10]scale=1920:1080[base_1080]; \
[vsplit11]scale=1280:720[base_720]; \
[vsplit12]scale=640:360[base_360]" \
\
-map "[video_1080_4.1]" \
-r:v:0 "24000/1001" \
-c:v:0 "libx264" \
-x264-params:0 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:0 "slow" \
-profile:v:0 "high" \
-level:v:0 "4.1" \
-refs:v:0 "2" \
-b-pyramid:v:0 "strict" \
-tune:v:0 "film" \
-b:v:0 "4800000" \
-maxrate:v:0 "4800000" \
-bufsize:v:0 "6*4800000/8" \
-vsync:v:0 "cfr" \
-bsf:v:0 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_720_4.1]" \
-r:v:1 "24000/1001" \
-c:v:1 "libx264" \
-x264-params:1 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:1 "slow" \
-profile:v:1 "main" \
-level:v:1 "4.1" \
-refs:v:1 "2" \
-b-pyramid:v:1 "strict" \
-tune:v:1 "film" \
-b:v:1 "3200000" \
-maxrate:v:1 "3200000" \
-bufsize:v:1 "6*3200000/8" \
-vsync:v:1 "cfr" \
-bsf:v:1 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_720_3.1]" \
-r:v:2 "24000/1001" \
-c:v:2 "libx264" \
-x264-params:2 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:2 "slow" \
-profile:v:2 "main" \
-level:v:2 "3.1" \
-refs:v:2 "2" \
-b-pyramid:v:2 "strict" \
-tune:v:2 "film" \
-b:v:2 "2200000" \
-maxrate:v:2 "2200000" \
-bufsize:v:2 "6*2200000/8" \
-vsync:v:2 "cfr" \
-bsf:v:2 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_540_3.1]" \
-r:v:3 "24000/1001" \
-c:v:3 "libx264" \
-x264-params:3 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:3 "slow" \
-profile:v:3 "main" \
-level:v:3 "3.1" \
-refs:v:3 "2" \
-b-pyramid:v:3 "strict" \
-tune:v:3 "film" \
-b:v:3 "1400000" \
-maxrate:v:3 "1400000" \
-bufsize:v:3 "6*1400000/8" \
-vsync:v:3 "cfr" \
-bsf:v:3 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_432_3.1]" \
-r:v:4 "24000/1001" \
-c:v:4 "libx264" \
-x264-params:4 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:4 "slow" \
-profile:v:4 "main" \
-level:v:4 "3.1" \
-refs:v:4 "2" \
-b-pyramid:v:4 "strict" \
-tune:v:4 "film" \
-b:v:4 "900000" \
-maxrate:v:4 "900000" \
-bufsize:v:4 "6*900000/8" \
-vsync:v:4 "cfr" \
-bsf:v:4 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_270_3.0]" \
-r:v:5 "24000/1001" \
-c:v:5 "libx264" \
-x264-params:5 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:5 "slow" \
-profile:v:5 "baseline" \
-level:v:5 "3.0" \
-refs:v:5 "2" \
-b-pyramid:v:5 "strict" \
-tune:v:5 "film" \
-b:v:5 "400000" \
-maxrate:v:5 "400000" \
-bufsize:v:5 "6*400000/8" \
-vsync:v:5 "cfr" \
-bsf:v:5 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_270_3.1]" \
-r:v:6 "24000/1001" \
-c:v:6 "libx264" \
-x264-params:6 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:6 "slow" \
-profile:v:6 "main" \
-level:v:6 "3.1" \
-refs:v:6 "2" \
-b-pyramid:v:6 "strict" \
-tune:v:6 "film" \
-b:v:6 "200000" \
-maxrate:v:6 "200000" \
-bufsize:v:6 "6*200000/8" \
-vsync:v:6 "cfr" \
-bsf:v:6 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_144_4.1]" \
-r:v:7 "24000/1001" \
-c:v:7 "libx264" \
-x264-params:7 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:7 "slow" \
-profile:v:7 "high" \
-level:v:7 "4.1" \
-refs:v:7 "2" \
-b-pyramid:v:7 "strict" \
-tune:v:7 "film" \
-b:v:7 "64000" \
-maxrate:v:7 "64000" \
-bufsize:v:7 "6*64000/8" \
-vsync:v:7 "cfr" \
-bsf:v:7 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[video_144_3.0]" \
-r:v:8 "24000/1001" \
-c:v:8 "libx264" \
-x264-params:8 "keyint=144:min-keyint=144:scenecut=0:open_gop=0" \
-preset:v:8 "slow" \
-profile:v:8 "baseline" \
-level:v:8 "3.0" \
-refs:v:8 "2" \
-b-pyramid:v:8 "strict" \
-tune:v:8 "film" \
-b:v:8 "56000" \
-maxrate:v:8 "56000" \
-bufsize:v:8 "6*56000/8" \
-vsync:v:8 "cfr" \
-bsf:v:8 "h264_metadata=fixed_frame_rate_flag=1" \
\
-map "[base_1080]" \
-c:v:9 "libx264" \
-preset:v:9 "slow" \
\
-map "[base_720]" \
-c:v:10 "libx264" \
-preset:v:10 "slow" \
\
-map "[base_360]" \
-c:v:11 "libx264" \
-preset:v:11 "slow" \
\
-map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 -map a:0 \
-c:a "libfdk_aac" \
-ar "48000" \
-ab "128k" \
-af "aresample=async=1:min_hard_comp=0.100000:first_pts=0" \
\
-f tee \
-flags +global_header \
"[select=\'v:0,a:0,v:1,a:1,v:2,a:2,v:3,a:3,v:4,a:4,v:5,a:5,v:6,a:6,v:7,a:7,v:8,a:8\':f=hls:hls_flags=discont_start+temp_file:hls_time=6:hls_list_size=0:var_stream_map=\'v:0,a:0 v:1,a:1 v:2,a:2 v:3,a:3 v:4,a:4 v:5,a:5 v:6,a:6 v:7,a:7 v:8,a:8\':master_pl_name=playlist.m3u8:hls_segment_filename=INPUT_VIDEO__%v_%03d.ts]INPUT_VIDEO/out_%v.m3u8|[select=\'v:9,a:9\':f=mp4:movflags=+faststart]INPUT_VIDEO/large-1920-1080.mp4|[select=\'v:10,a:10\':f=mp4:movflags=+faststart]INPUT_VIDEO/med-1280-720.mp4|[select=\'v:11,a:11\':f=mp4:movflags=+faststart]INPUT_VIDEO/sm-640-360.mp4"