Recherche avancée

Sur d’autres sites (13281)

• How to display a stream of mdat/moof boxes in VLC ? [closed]

  8 juillet 2024, par roacs

  I am trying to display a real-time video stream in VLC. The snag is that the real-time video that is being received is a stream of just the mdat and moof boxes of a fragmented MP4 file that is being recorded elsewhere. The initialization information (ftyp/moov) is not and will never be available in the real-time stream. There is also no audio.

  


  I have access to initialization information (ftyp/moov) of a previously completed file and can use that to aid in the processing/streaming of the real-time mdat/moof boxes.

  


  I am currently extracting the contents of the mdat box, splitting those up and packaging them in 188 byte MPEG-TS packets and multicasting them for VLC to pick up. And just as a shot in the dark, every 50 mdat's I am also packaging the SPS and PPS NALUs from the initialization information of the completed file and multicasting those in one MPEG-TS packet.

  


  Input looks like this :

  


  

  • ...

  


  • mdat 1

  


  • moof 1

  


  • mdat 2

  


  • moof 2

  


  • ...

  


  • mdat N

  


  • moof N

  


  • ...

  


  


  And my output looks like this :

  


  

  • ...

  


  • MPEG-TS 1 containing first 184 bytes of mdat 1

  


  • MPEG-TS 2 containing next 184 bytes of mdat 1

  


  • ...

  


  • MPEG-TS N containing last 184 bytes of mdat 1

  


  • MPEG-TS N+1 containing first 184 bytes of mdat 2

  


  • MPEG-TS N+2 containing next 184 bytes of mdat 2

  


  • ...

  


  • MPEG-TS N+M containing last 184 bytes of mdat 2

  


  • ...

  


  • MPEG-TS containing SPS and PPS NALU

  


  • ...

  


  


  VLC gets the data but no video playback.

  


  How do I process this input in order to get it to play in VLC ?

  


• I can't start dream recording ? [closed]

  5 mars 2024, par usny1986

  I'm looking for an app to record my dreams so i can watch them later. (I want it to record speech sounds too). The apps i've tried so far haven't worked properly.

  


  When I start to see my dream, the applications usually give an error that ffmpeg is not installed. Yes, this error doesn't occur if I dream in the dark at night. But the problem is that i sleep during the day, so i dream during the day. Even though I installed the latest version of FFmpeg, I was not successful.

  


  Is there a successful app to record daytime dreams ?

  


  I tried the "HD Dream Captura" application. But it didn't work. It doesn't work during the day. It also gives a memory full error and is constantly interrupted. But I have enough free space in my brain to be able to see my dreams.

  


• Is it possible to use the signalstats YAVG filter in FFMPEG to control the gamma correction in a video ? [migrated]

  27 décembre 2023, par tuqueque

  I don't know if this is even possible, but something tells me it is… You see, I want to dynamically control the gamma correction in FFMPEG/FFPLAY depending on how bright/dark the frame being reproduced in a video/movie is…

  


  For context, there's a filter in FFMPEG/FFPLAY/FFPROBE called signalstats that reports various useful sets of info about the video being processed/reproduced/analized. There's a YAVG parameter in the signalstats filter that returns the average luma level of the frame (https://ffmpeg.org/ffmpeg-filters.html#signalstats-1) . This is what I want to use to determine/calculate the gamma value to use in the eq filter gamma (https://ffmpeg.org/ffmpeg-filters.html#eq)… For example, in the end, I would like to use a formula like "1-(YAVG/50)+1"…

  


  With the signalstats YAVG filter/parameter I've managed to do these unrelated exercises :

  


  Analyze (with FFPROBE) a video and write a log file with the YAVG value for each frame :

  


  ffprobe -f lavfi movie=VIDEO_INPUT,signalstats -show_entries frame_tags=lavfi.signalstats.YAVG -of csv="p=0" > YAVG.log


  


  I have been able to also play a video (with FFPLAY) and show in the upper-left corner the YAVG values for each frame being reproduced :

  


  First, we need to create a text file in the home folder called in this case "signalstat_drawtext.txt" with the following content :

  


      %{metadata:lavfi.signalstats.YAVG}


  


  Then, we run this command :

  


      ffplay VIDEO_INPUT -vf signalstats,drawtext=fontfile=FreeSerif.ttf:fontcolor=lime:textfile=signalstat_drawtext.txt


  


  However, I haven't been able to find/guess how to use the YAVG output to control (in realtime) the gamma value in the eq filter… I think it's possible, I just don't know how to write the command.

  


  Using FFPLAY, I would imagine something like this :

  


  ffplay VIDEO_INPUT -vf signalstats,eq=gamma="1-(metadata:lavfi.signalstats.YAVG/50)+1":eval=frame


  


  But of course, this doesn't work and I'm sure I'm just writing nonsense.