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• FFMPEG streaming RTP : time base not set

  25 octobre 2020, par Managarm

  I'm trying to create a small demo to get a feeling for streaming programmatically with ffmpeg. I'm using the code from this question as a basis. I can compile my code, but when I try to run it I always get this error :

  



  


  [rtp @ 0xbeb480] time base not set

  


  



  The thing is, I have set the time base parameters. I even tried setting them for the stream (and the codec associated with the stream) as well, even though this should not be necessary as far as I understand it. This is the relevant section in my code :

  



  AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
AVCodecContext* c = avcodec_alloc_context3(codec);
c->pix_fmt = AV_PIX_FMT_YUV420P;
c->flags = CODEC_FLAG_GLOBAL_HEADER;
c->width = WIDTH;
c->height = HEIGHT;
c->time_base.den = FPS;
c->time_base.num = 1;
c->gop_size = FPS;
c->bit_rate = BITRATE;

avcodec_open2(c, codec, NULL);
struct AVStream* stream = avformat_new_stream(avctx, codec);

// TODO: causes an error
avformat_write_header(avctx, NULL);


  



  The error occurs when calling "avformat_write_header" near the end. All methods that can fail (like avcodec_open2) are checked, I just removed the checks to make the code more readable.

  



  Digging through google and the ffmpeg source code didn't yield any useful results. I think it's really basic, but I'm stuck. Who can help me ?

  


• FFMPEG streaming RTP : time base not set

  15 novembre 2016, par Managarm

  I’m trying to create a small demo to get a feeling for streaming programmatically with ffmpeg. I’m using the code from this question as a basis. I can compile my code, but when I try to run it I always get this error :

  [rtp @ 0xbeb480] time base not set

  The thing is, I have set the time base parameters. I even tried setting them for the stream (and the codec associated with the stream) as well, even though this should not be necessary as far as I understand it. This is the relevant section in my code :

  AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  AVCodecContext* c = avcodec_alloc_context3(codec);
  
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  c->flags = CODEC_FLAG_GLOBAL_HEADER;
  
  c->width = WIDTH;
  
  c->height = HEIGHT;
  
  c->time_base.den = FPS;
  
  c->time_base.num = 1;
  
  c->gop_size = FPS;
  
  c->bit_rate = BITRATE;
  
  
  
  avcodec_open2(c, codec, NULL);
  
  struct AVStream* stream = avformat_new_stream(avctx, codec);
  
  
  
  // TODO: causes an error
  
  avformat_write_header(avctx, NULL);

  The error occurs when calling "avformat_write_header" near the end. All methods that can fail (like avcodec_open2) are checked, I just removed the checks to make the code more readable.

  Digging through google and the ffmpeg source code didn’t yield any useful results. I think it’s really basic, but I’m stuck. Who can help me ?

• bash variable changes in loop with ffmpeg

  17 septembre 2018, par Mike

  I wrote a skript to quickly create short preview clips from vides I recorded on timestamps that I found worth checking out later for cutting.
  My file with the timestamps is written like this

  FILE_NAME1#MM:SS MM:SS
  
  FILE_NAME2#MM:SS MM:SS MM:SS MM:SS

  example :

  MAH01728#02:47 03:34 03:44 05:00 06:08 06:55

  The script looks like this :

  #!/bin/bash
  
  while read f
  
   do
  
  
  
   file=$(echo $f | cut -d"#" -f1)
  
   filename=${file}".MP4"
  
   timestamps=$(echo $f | cut -d"#" -f2)
  
  
  
  for time in $timestamps 
  
   do 
  
    ffmpeg -ss 00:${time}.0 -i "orig/${filename}" -c copy -t 10 "preview/${file}_${time}.MP4"
  
   done
  
  done < $1

  The script gets half of the previews that I want and on the other the filename is messed up and ffmpeg complains that the file is not found :

  orig/714.MP4: No such file or directory
  
  orig/00:58 01:25.MP4: No such file or directory

  So I modified the script for trouble shooting and just put an echo in front of the ffmpeg command - now all file names are correct. What am I missing ?

  ffmpeg -ss 00:01:47.0 -i orig/MAH01714.MP4 -c copy -t 10 preview/MAH01714_01:47.MP4
  
  ffmpeg -ss 00:02:00.0 -i orig/MAH01713.MP4 -c copy -t 10 preview/MAH01713_02:00.MP4
  
  ffmpeg -ss 00:00:58.0 -i orig/MAH01712.MP4 -c copy -t 10 preview/MAH01712_00:58.MP4
  
  ffmpeg -ss 00:01:25.0 -i orig/MAH01712.MP4 -c copy -t 10 preview/MAH01712_01:25.MP4