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• Concatenating multiple remote files using ffmpeg ?

  8 décembre 2018, par May Rest in Peace

  I am trying to concatenate multiple remote files using ffmpeg but some files get skipped in the output.

  I use the command

  ffmpeg -f concat -safe 0 -protocol_whitelist "file,http,https,tcp,tls" -i mylist.txt -c copy output.m4a

  mylist.txt looks like :

  file 'http://remoteurl?fileName=20.m4a'
  
  file 'http://remoteurl?fileName=21.m4a'
  
  file 'http://remoteurl?fileName=22.m4a'
  
  file 'http://remoteurl?fileName=23.m4a'

  On running this command, the output will contain audio from only some files.

  I download the files individually from the same urls and did a local concatentation using the same command and it worked perfectly.

  Is this because concat will not work if files are not present immediately as mentioned in https://trac.ffmpeg.org/wiki/Concatenate#Automaticallyappendingtothelistfile ?

  If that’s the case then how should I proceed ? There’s a terminal script provided in the above link but I am on a Windows machine and tbh, I am not that good at bash scripting.

  All files are audio files with same bitrate and are in .m4a format.

  This is the error message I receive [mov,mp4,m4a,3gp,3g2,mj2 @ 00000278b64d4f40] stream 0, offset 0xc9b: partial file

• 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