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• Encode video with FFmpeg fps have been wrong

  7 novembre 2016, par Burak Hamuryen

  I’m trying to encod a video with FFmpeg but i have a problem about fps.
  So i build the sample code as follows

  AVCodec *codec;
  
  AVCodecContext *c = NULL;
  
  int i, ret, x, y, got_output;
  
  FILE *f;
  
  AVFrame *frame;
  
  AVPacket pkt;
  
  uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
  printf("Encode video file %s\n", filename);
  
  
  
  /* find the mpeg1 video encoder */
  
  codec = avcodec_find_encoder((AVCodecID)codec_id);
  
  if (!codec) {
  
      fprintf(stderr, "Codec not found\n");
  
      exit(1);
  
  }
  
  
  
  c = avcodec_alloc_context3(codec);
  
  if (!c) {
  
      fprintf(stderr, "Could not allocate video codec context\n");
  
      exit(1);
  
  }
  
  
  
  /* 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.num = 1;
  
  c->time_base.den = 5; //changed
  
  
  
  /* emit one intra frame every ten frames
  
  * check frame pict_type before passing frame
  
  * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
  
  * then gop_size is ignored and the output of encoder
  
  * will always be I frame irrespective to gop_size
  
  */
  
  c->gop_size = 10;
  
  c->max_b_frames = 1;
  
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
  if (codec_id == AV_CODEC_ID_H264)
  
      av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
  /* open it */
  
  if (avcodec_open2(c, codec, NULL) < 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);
  
  }
  
  
  
  frame = av_frame_alloc();
  
  if (!frame) {
  
      fprintf(stderr, "Could not allocate video frame\n");
  
      exit(1);
  
  }
  
  frame->format = c->pix_fmt;
  
  frame->width = c->width;
  
  frame->height = c->height;
  
  
  
  /* the image can be allocated by any means and av_image_alloc() is
  
  * just the most convenient way if av_malloc() is to be used */
  
  ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
  
      c->pix_fmt, 32);
  
  if (ret < 0) {
  
      fprintf(stderr, "Could not allocate raw picture buffer\n");
  
      exit(1);
  
  }
  
  
  
  /* encode 5 second of video */
  
  for (i = 0; i < 25; i++) {
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;    // packet data will be allocated by the encoder
  
      pkt.size = 0;
  
  
  
      fflush(stdout);
  
      /* prepare a dummy image */
  
      /* Y */
  
      for (y = 0; y < c->height; y++) {
  
          for (x = 0; x < c->width; x++) {
  
              frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
  
          }
  
      }
  
  
  
      /* Cb and Cr */
  
      for (y = 0; y < c->height / 2; y++) {
  
          for (x = 0; x < c->width / 2; x++) {
  
              frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
  
              frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
  
          }
  
      }
  
  
  
      frame->pts = i;
  
  
  
      /* encode the image */
  
      ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
  
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  /* get the delayed frames */
  
  for (got_output = 1; got_output; i++) {
  
      fflush(stdout);
  
  
  
      ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
  
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  /* add sequence end code to have a real mpeg file */
  
  fwrite(endcode, 1, sizeof(endcode), f);
  
  fclose(f);
  
  
  
  avcodec_close(c);
  
  av_free(c);
  
  av_freep(&frame->data[0]);
  
  av_frame_free(&frame);
  
  printf("\n");

  and I changed the following parts from the original

  c->time_base.num = 1;
  
  c->time_base.den = 5;

  after these changes, i expect a video to be composed of 5 seconds and 5 fps.
  But when i play the output video file, the video ends in 1 2 seconds.
  The ffprob output of output video is as follows.

  Edit :
  ffprobe output added as a text

  ffprobe version 2.0.1 Copyright (c) 2007-2013 the FFmpeg developers
  
    built on Sep 26 2013 02:00:03 with gcc 4.8.1 (GCC)
  
    configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
    libavutil      52. 38.100 / 52. 38.100
  
    libavcodec     55. 18.102 / 55. 18.102
  
    libavformat    55. 12.100 / 55. 12.100
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 79.101 /  3. 79.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, h264, from 'C:\Users\bhamuryen\Desktop\Dev\Test\ffmpeg_test\ffmpeg_test\test.h264':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: h264 (High), yuv420p, 352x288, 5 fps, 5 tbr, 1200k tbn, 10 tbc
  
  [STREAM]
  
  index=0
  
  codec_name=h264
  
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  profile=High
  
  codec_type=video
  
  codec_time_base=1/10
  
  codec_tag_string=[0][0][0][0]
  
  codec_tag=0x0000
  
  width=352
  
  height=288
  
  has_b_frames=1
  
  sample_aspect_ratio=0:1
  
  display_aspect_ratio=0:1
  
  pix_fmt=yuv420p
  
  level=13
  
  timecode=N/A
  
  id=N/A
  
  r_frame_rate=10/2
  
  avg_frame_rate=5/1
  
  time_base=1/1200000
  
  start_pts=N/A
  
  start_time=N/A
  
  duration_ts=N/A
  
  duration=N/A
  
  bit_rate=N/A
  
  nb_frames=N/A
  
  nb_read_frames=N/A
  
  nb_read_packets=N/A
  
  DISPOSITION:default=0
  
  DISPOSITION:dub=0
  
  DISPOSITION:original=0
  
  DISPOSITION:comment=0
  
  DISPOSITION:lyrics=0
  
  DISPOSITION:karaoke=0
  
  DISPOSITION:forced=0
  
  DISPOSITION:hearing_impaired=0
  
  DISPOSITION:visual_impaired=0
  
  DISPOSITION:clean_effects=0
  
  DISPOSITION:attached_pic=0

  The output video file played with VLC and VLC statistic is as follows.

  

  As shown, i setted fps 5 but vlc read it like 10 fps also ffprobe say to us

  Stream #0:0 : Video : h264 (High), yuv420p, 352x288, 5 fps, 5 tbr, 1200k tbn, 10 tbc

  and

  codec_time_base=1/10

  i think the important thing is codec_time_base=1/10 and 10 tbc.
  What is wrong in this code ? i don’t know exactly the reason for the problem.
  How can i create a video(5 fps -10 fps or custom fps) and play correctly the created video ?

  Thanks for your help.

• How to encode H.264 video using FFmpeg C API and then open the output with a media player ?

  4 avril 2016, par GummiB

  I’m trying to encode a H.264 video with the FFMPEG C API.
  I have successfully compiled and executed the decoding/encoding example provided by FFMPEG.

  The problem I’m facing is that the .mpg file (encoded with AV_CODEC_ID_MPEG1VIDEO) the example creates works. Windows creates a thumbnail and everything. On the other hand the .h264 (encoded with AV_CODEC_ID_H264) file does not. When I try to play the file in VLC the play/pause button just flickers, no thumbnail in windows, no nothing.

  During encoding libx264 reports the following :

  [libx264 @ 004b81a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 004b81a0] profile High, level 1.3
  
  [libx264 @ 004b81a0] frame I:3     Avg QP:26.79  size:  2116
  
  [libx264 @ 004b81a0] frame P:12    Avg QP:26.60  size:   789
  
  [libx264 @ 004b81a0] frame B:10    Avg QP:31.39  size:   499
  
  [libx264 @ 004b81a0] consecutive B-frames: 20.0% 80.0%
  
  [libx264 @ 004b81a0] mb I  I16..4: 78.3% 11.6% 10.1%
  
  [libx264 @ 004b81a0] mb P  I16..4: 77.4%  0.6%  0.1%  P16..4: 20.3%  0.7%  0.9%  0.0%  0.0%    skip: 0.0%
  
  [libx264 @ 004b81a0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  9.4%  0.2%  0.0%  direct:11.0%  skip:79.4%  L0:25.4% L1:35.4% BI:39.2%
  
  [libx264 @ 004b81a0] final ratefactor: 17.03
  
  [libx264 @ 004b81a0] 8x8 transform intra:3.4% inter:31.3%
  
  [libx264 @ 004b81a0] direct mvs  spatial:0.0% temporal:100.0%
  
  [libx264 @ 004b81a0] coded y,uvDC,uvAC intra: 4.4% 35.8% 1.6% inter: 1.3% 34.5% 9.5%
  
  [libx264 @ 004b81a0] i16 v,h,dc,p:  0%  0%  0% 100%
  
  [libx264 @ 004b81a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  7% 20% 17% 49%  0%  0%  0%  1%  6%
  
  [libx264 @ 004b81a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 14%  7% 18% 45%  2%  7%  2%  3%  2%
  
  [libx264 @ 004b81a0] i8c dc,h,v,p:  2%  6%  4% 88%
  
  [libx264 @ 004b81a0] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 004b81a0] ref P L0: 95.6%  1.6%  2.2%  0.5%  0.2%
  
  [libx264 @ 004b81a0] ref B L0: 67.5% 28.5%  3.2%  0.8%
  
  [libx264 @ 004b81a0] kb/s:166.45

  "ffprobe.exe test.h264 -show_streams" returns

  [STREAM]
  
  index=0
  
  codec_name=h264
  
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  profile=High
  
  codec_type=video
  
  codec_time_base=1/50
  
  codec_tag_string=[0][0][0][0]
  
  codec_tag=0x0000
  
  width=352
  
  height=288
  
  has_b_frames=1
  
  sample_aspect_ratio=0:1
  
  display_aspect_ratio=0:1
  
  pix_fmt=yuv420p
  
  level=13
  
  timecode=N/A
  
  id=N/A
  
  r_frame_rate=50/2
  
  avg_frame_rate=25/1
  
  time_base=1/1200000
  
  start_pts=N/A
  
  start_time=N/A
  
  duration_ts=N/A
  
  duration=N/A
  
  bit_rate=N/A
  
  nb_frames=N/A
  
  nb_read_frames=N/A
  
  nb_read_packets=N/A
  
  DISPOSITION:default=0
  
  DISPOSITION:dub=0
  
  DISPOSITION:original=0
  
  DISPOSITION:comment=0
  
  DISPOSITION:lyrics=0
  
  DISPOSITION:karaoke=0
  
  DISPOSITION:forced=0
  
  DISPOSITION:hearing_impaired=0
  
  DISPOSITION:visual_impaired=0
  
  DISPOSITION:clean_effects=0
  
  DISPOSITION:attached_pic=0
  
  [/STREAM]

  There you can see :

  start_time=N/A
  
  duration_ts=N/A
  
  duration=N/A

  I have tried countless changes to the AVCodecContext and multitude of parameters options to av_opt_set function. Still no luck getting a working H.264 video. I have even tried different builds of FFmpeg. No luck.

  I’m using the "FFmpeg git-0fb64da 32-bit Dev" build from Zeranoe and MinGw 4.7.2

• FFmpeg only reading one channel

  29 août 2017, par AbstractDissonance

  Trying to read a stereo wav file and ffmpeg is only reading one channel. ffprobe returns 2 channels.

  I have used -ac 2 and then added -channel_layout stereo but all return 1 channel(or basically filling half the buffer I created).

  Basically the output size of ffmpeg is about half the wav file size.

  What I would like is for it to return every channel in

  Channel1_sample1, channel2_sample1, ..., ChannelN_sample1, channel1_sample2, etc...

  But, in reality, I’d rather just have it work with stereo ;) I’m giving it plenty large enough buffer to read to, so that isn’t the problem either.

  Here is the output

  ffprobe.exe -hide_banner -v quiet -print_format flat -show_streams -i temp.wav
  
  streams.stream.0.index=0
  
  streams.stream.0.codec_name="pcm_s16le"
  
  streams.stream.0.codec_long_name="PCM signed 16-bit little-endian"
  
  streams.stream.0.profile="unknown"
  
  streams.stream.0.codec_type="audio"
  
  streams.stream.0.codec_time_base="1/44100"
  
  streams.stream.0.codec_tag_string="[1][0][0][0]"
  
  streams.stream.0.codec_tag="0x0001"
  
  streams.stream.0.sample_fmt="s16"
  
  streams.stream.0.sample_rate="44100"
  
  streams.stream.0.channels=2
  
  streams.stream.0.channel_layout="unknown"
  
  streams.stream.0.bits_per_sample=16
  
  streams.stream.0.id="N/A"
  
  streams.stream.0.r_frame_rate="0/0"
  
  streams.stream.0.avg_frame_rate="0/0"
  
  streams.stream.0.time_base="1/44100"
  
  streams.stream.0.start_pts="N/A"
  
  streams.stream.0.start_time="N/A"
  
  streams.stream.0.duration_ts=14200200
  
  streams.stream.0.duration="322.000000"
  
  streams.stream.0.bit_rate="1411200"
  
  streams.stream.0.max_bit_rate="N/A"
  
  streams.stream.0.bits_per_raw_sample="N/A"
  
  streams.stream.0.nb_frames="N/A"
  
  streams.stream.0.nb_read_frames="N/A"
  
  streams.stream.0.nb_read_packets="N/A"
  
  streams.stream.0.disposition.default=0
  
  streams.stream.0.disposition.dub=0
  
  streams.stream.0.disposition.original=0
  
  streams.stream.0.disposition.comment=0
  
  streams.stream.0.disposition.lyrics=0
  
  streams.stream.0.disposition.karaoke=0
  
  streams.stream.0.disposition.forced=0
  
  streams.stream.0.disposition.hearing_impaired=0
  
  streams.stream.0.disposition.visual_impaired=0
  
  streams.stream.0.disposition.clean_effects=0
  
  streams.stream.0.disposition.attached_pic=0
  
  streams.stream.0.disposition.timed_thumbnails=0
  
  ffmpeg.exe -i temp.wav -loglevel quiet -f s16le -ac 2 -channel_layout stereo -

  temp.wav is just a standard stereo wav file.