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• ffmpeg in:h264 out:yuv to stdout - data format ?

  27 février 2019, par Petr

  I am (like many) trying to get a continuous series of still images out of the camera attached to a raspberry pi. I want to do this in java for all the usual reasons, and am using a Runtime exec command to pipe the output of raspivid to the following ffmpeg command, and then collecting the result via stdout --- note xxx.h264 is a test file generated by the camera that does not play because there is no container, but I am getting images out so half good.

  ffmpeg -i xxx.h264 -vcodec rawvideo -r 2 -pix_fmt yuv420p -f nut -

  I have some code displaying the frames, but they "march" across the display area from left to right, and there appears to be a growing amount of rubbish across the top of the images. I have looked at the bytes it outputs by running the same command and redirecting it into a file, then using vi/xxd and find that there is headder material ("nut/multimedia container ...").

  I am guessing that there is more metadata inserted by my ffmpeg command, that I am failing to remove when processing the raw yuv420p data as described here : https://en.wikipedia.org/wiki/YUV#Y%E2%80%B2UV420sp_%28NV21%29_to_RGB_conversion_%28Android%29

  For the life of me I cannot find the nut documentation anywhere in a readable format and anyway, it seems that is not what I should be looking for. Any pointers as to how I can recognise the frame boundaries in my byte stream ?

• rtl_fm piped to ffmpeg for udp stream

  4 novembre 2014, par user3936148

  rtl_fm piped to ffmpeg for udp stream

  Using Windows 7. I would like to pipe the rtl_fm standard out (pipe) to ffmpeg and udp stream it to an ip address. I have downloaded and installed rlt_sdr and other files and I have also installed sox. The console example given with the rtl_fm application using sox to play the radio station is below :

  rtl_fm -f 106500000 -M wbfm -s 200000 -r 48000 -l 0 -E deemp -g 50 - | play -r 48000 -t s16 -L -c 1 -

  This works great, using sox.

  Update :

  Below works with ffplay sounds ok not great..

  rtl_fm -f 106500000 -M wbfm -s 200000 -r 48000 -l 0 -E deemp -g 80- | ffplay -f s16le -ar 48000 -ac 1 -

  I would like to use ffmpeg instead, below is a non working example (just to give you an idea)

  rtl_fm -f 106500000 -M wbfm -s 200000 -r 48000 -l 0 -E deemp -g 50 - | ffmpeg -i - -f s16le -ar 48000 -ac 1 -acodec libmp3lame -ab 24k -ar 22050 -f mpegts udp ://192.168.1.196:1234 -

  useful links :

  http://kmkeen.com/rtl-demod-guide/

  http://sdr.osmocom.org/trac/wiki/rtl-sdr

  Thank you for your help

• FFMPEG throwing error nb_cpb invalid, what went wrong ?

  21 août 2023, par qkhanhpro

  I am trying to play with this file from Kodi sample page https://kodi.wiki/view/Samples

  


  


  HDR10+ Profile A HEVC 10-bit 23.976 Sample (in MKV with DTS:X audio)

  


  


  The ffmpeg command throw this error on every line, with the number always being 93 for multiple different output video codec

  


  nb_cpb 93 invalid.0 q=0.0 size=       0kB time=00:00:00.65 bitrate=   0.5kbits/s speed=3.95x  


  


  A search point to this source file https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/hevc_ps.c

  


  if (!hdr->flags.low_delay_hrd_flag) {
    hdr->cpb_cnt_minus1[i] = get_ue_golomb_long(gb);
    if (hdr->cpb_cnt_minus1[i] > 31) {
        av_log(NULL, AV_LOG_ERROR, "nb_cpb %d invalid\n",
               hdr->cpb_cnt_minus1[i]);
        return AVERROR_INVALIDDATA;
    }
}


  


  What went wrong ?

  


  ffmpeg -i E:\HDR.mkv -c:v libx265 -c:a copy "HDR.mp4" 

ffmpeg -i E:\HDR.mkv -c:v hevc_nvenc -c:a copy "HDR.mp4"