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Autres articles (60)

  • Websites made ​​with MediaSPIP

    2 mai 2011, par

    This page lists some websites based on MediaSPIP.

  • Creating farms of unique websites

    13 avril 2011, par

    MediaSPIP platforms can be installed as a farm, with a single "core" hosted on a dedicated server and used by multiple websites.
    This allows (among other things) : implementation costs to be shared between several different projects / individuals rapid deployment of multiple unique sites creation of groups of like-minded sites, making it possible to browse media in a more controlled and selective environment than the major "open" (...)

  • Des sites réalisés avec MediaSPIP

    2 mai 2011, par

    Cette page présente quelques-uns des sites fonctionnant sous MediaSPIP.
    Vous pouvez bien entendu ajouter le votre grâce au formulaire en bas de page.

Sur d’autres sites (8993)

  • What really causes stutter in RTSP stream ? Live555/FFMPEG server, Android Client

    2 mars 2015, par Wajih

    Ok,I am going to ask you a few simple questions after I had some lengthy arguments with my manager. I am not going to post lengthy code snippets, but just try to explain what I know and I know someone can guide me.

    1. I am working on a opensource project that contains two different streaming servers, FFMPEG and Live555. Both stream H264 video over UDP
    2. I can easily switch between the two and the client seems to understands which server it is talking to.
    3. At the android client, the code uses hardware decoding via MediaCodec apis for Android SDK 4.1.2

    From this point onward I have been arguing with my manager that video breakage and stutter are two different things, where breakage is caused by packet loss over the network. And stutter is completely different, though my knowledge about stutter is limited, I could not argue much so I turned to SO.

    I am not really sure as to why stutter is frequently occuring. Even at 0% 1% packet loss, packets encoded as H264 stream are being received at Android Client - Client tries to decode the stream and render it. I did not expect stutter to occur so frequently and so badly. I feel it sometimes even induces lag or delay in video play by couple of seconds. Stutter occurs after almost every minute or so.

    I am not really into H.264 streaming or H264 codec - both are new to me.
    May be someone can guide me in the right direction, any possibility that stutter occurs due to re-transmission of UDP packets ?

  • avfilter/af_compand : fix clipping with default options

    17 juillet 2015, par Paul B Mahol
    avfilter/af_compand : fix clipping with default options

    Decays and attacks where by default set only for first channel
    
which caused poor defaults to be used which produced clipping
    
on any higher channel.
    

    Reported-by : lachs0r
    
Signed-off-by : Paul B Mahol <onemda@gmail.com>
    • [DH] doc/filters.texi
    • [DH] libavfilter/af_compand.c

  • PSNR calculated with ffmpeg behaviours unexpected

    16 mars 2017, par muuh

    I’m trying to calculated the PSNR (Peak Signal to Noise Ratio) between to videos with ffmpeg.
    The basic command is : ffmpeg -i reference.avi -candidate.avi -filter_complex "psnr" out.avi.
    If I swap reference.avi and candidate.avi in the command, ffmpeg returns me a different PSNR value. The PSNR is utilizing the mean squared error between the frames, so the order should be irrelevant.

    According to this answer, this could be caused by different frame rates (or other mismatches in the video).

    The suggested code

    ffmpeg -i file1 -i file2 \
       -lavfi '[0:v]setpts=N[out0];[1:v]setpts=N[out1];[out0][out1]psnr' \
       -f null -v info -

    does not solve the issue.
    Further, in my case, candidate.avi are recoded copies of reference.avi(*). They have identical framerates and exactly same runtime. I also validated this with avprobe.

    Another possibility I think I can exclude are rounding errors. The results sometimes change from 49dB to 64dB [sic !] dependent on the order of input.

    How do I calculate the PRNU correctly with ffmpeg, and what is the reason for this behaviour ?

    (*) Recoding done for example with : ffmpeg -i reference.avi -c:v huffyuv candidate.avi

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