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• ffmpeg - create a video from a sprite

  27 septembre 2018, par Guig

  I’ve an image that represents a short animation as 40 frames in 5 rows 8 columns. How can I use ffmpeg to generate a video from this ?

  I’ve read that answer to generate a video from a list of images but I’m unsure about how to tell ffmpeg to read parts of a single image in sequence.

• How to set frame offset for source and reference video for calculating using FFMpeg commandline ?

  1er septembre 2018, par Souvik Das

  I have a scenario where I am streaming a reference video on a server machine and receiving it at a client machine with exact same codec, using FFMpeg via UDP/RTP.

  So, I have a reference.avi file and a recording.ts file with me. Now, due to a network side issue and FFMpeg discarding old frames, often the recording.ts lacks exactly 12 FRAMES from the beginning. Sometimes, it may lack more frames in-between but that’d due to general network traffic and packet loss reason and I don’t plan to account for that. Anyways, due to those 12 frames, when I calculate the PSNR, it drops down to 13, even though remaining frames may/may not be affected.

  So, my aim is to discard first 12 frames from reference.ts and then compare. For that, I would also need to adjust the frames from recording.ts.

  Consider the following scenario :

  reference.ts has 1500 frames. So naturally I am going to cut-short it 1488. Then we have the following cases :

  1. recording.ts has 1500 frames. This is not affected. Still I will remove 12 frames to match the count. So frame 1 would then represent frame 13.
  2. recording.ts has 1496 frames. This is not affected. Still I will remove 12 frames even though it’d get to 1484 count assuming that frame 1 would then represent frame 13.
  3. recording.ts has 1488 frames. This is affected. No need to remove frames.
  4. recording.ts has 1480 frames. This is affected. No need to remove frames.

  Once that is done, then I will calcualte the PSNR. So, my FFMpeg should be able to do all this, hopefully in a single command on bash.

  A better alternative would be for FFMpeg to find the where the 13th frame is in recording.ts and then cut-short from the beginning. That’d be more preferred and even more if there is no cut-shorting required, i.e. if offset could be set in-line to command and no additional video output is generated for use in PSNR comparison.

  Current I am using the following command to calculate the PSNR.

  ffmpeg -i 'recording.ts' -vf "movie='reference.avi', psnr=stats_file='psnr.txt'" -f rawvideo -y /dev/null

  It’d be great if somebody could help me in this regard. Thanks.

• FFMPEG IP Camera Stream Recording

  26 août 2015, par Zohaib Khalid

  What is the short command for storing this input stream into some external file ?

  http://10.11.16.10:81/livestream.cgi?user=admin&pwd=&streamid=0&audio=0&filename=

  This is the input stream. Now I want to save it in new.mp4||.flv
  What would be the FFMPEG command ?