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Autres articles (31)

  • Publier sur MédiaSpip

    13 juin 2013

    Puis-je poster des contenus à partir d’une tablette Ipad ?
    Oui, si votre Médiaspip installé est à la version 0.2 ou supérieure. Contacter au besoin l’administrateur de votre MédiaSpip pour le savoir

  • Les formats acceptés

    28 janvier 2010, par

    Les commandes suivantes permettent d’avoir des informations sur les formats et codecs gérés par l’installation local de ffmpeg :
    ffmpeg -codecs ffmpeg -formats
    Les format videos acceptés en entrée
    Cette liste est non exhaustive, elle met en exergue les principaux formats utilisés : h264 : H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 m4v : raw MPEG-4 video format flv : Flash Video (FLV) / Sorenson Spark / Sorenson H.263 Theora wmv :
    Les formats vidéos de sortie possibles
    Dans un premier temps on (...)

  • Use, discuss, criticize

    13 avril 2011, par

    Talk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
    The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
    A discussion list is available for all exchanges between users.

Sur d’autres sites (6723)

  • How to get bit stream rate of a mpeg Transport Stream ?

    28 septembre 2015, par CompNet

    How can we get the bit rate of a transport stream from the TS source ? One way is to use a constant bitrate while multiplexing the encoded video into TS stream. But how does the variable bitstream work ?

    I found the command with ffmpeg like :

    ffmpeg -i encoded.mp4 -c copy -map 0 -vbsf h264_mp4toannexb mpegts out.ts

    but could not understand the meaning of -vbsf h264_mp4toannexb. Can anyone please explain me how does variable bitrate work ?

    Also, is there any other way we can find the timestamp of each TS packet multiplexed in the Transport Stream ?

  • how av_freep in ffmpeg works ?

    11 août 2016, par Billy Bob

    I have some questions regarding void pointer in C. I found out the following code, part of ffmpeg that I couldn’t understand... Could someone explain to me how it works ?

    void av_freep(void *arg)
    
{
    
        void *val;
    

    
        memcpy(&val, arg, sizeof(val));
    
        memcpy(arg, &(void *){ NULL }, sizeof(val));
    
        av_free(val);
    
}

    and later it’s called like this :

    char *str;
    
av_freep(&str);

    my questions :

    1. how passing address of str (&str) doesn’t trigger "incompatible type" warning when it’s compiled ? Shouldn’t &str type is become char** ?
    2. what’s the meaning of &(void *) NULL in one of memcpy parameter ?
    3. why it’s trying to free "val" which is not allocated ?

    Thanks !

  • FFMPEG API real-time encoding, skipped frames

    24 octobre 2015, par Paul Knopf

    I am using FFMPEG to encode live video. If I can’t keep up with the live encoding, I need to drop frames. Currently, I just skip the encoding of a raw frame, and the PTS for the next frame is the same. Meaning, even if there is a skipped frame, the pts is always 1,2,3,4,5,6....

    This causes the playback of the file to skip ahead in time. Instead, I would like to add blank frames to the muxed file. I tried making PTS indicate a skipped frame by setting it to 1,2,4,5,8,...., but the FFMPEG h264 encoders depend on PTS being consecutive.

    How do I pass empty data to my mp4/container, indicating a blank space in time, so that decoders won’t appear to jump ahead in time, but instead just see a delay/freeze.

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