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  • Keeping control of your media in your hands

    13 avril 2011, par

    The vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
    While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
    MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
    MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...)

  • Les tâches Cron régulières de la ferme

    1er décembre 2010, par

    La gestion de la ferme passe par l’exécution à intervalle régulier de plusieurs tâches répétitives dites Cron.
    Le super Cron (gestion_mutu_super_cron)
    Cette tâche, planifiée chaque minute, a pour simple effet d’appeler le Cron de l’ensemble des instances de la mutualisation régulièrement. Couplée avec un Cron système sur le site central de la mutualisation, cela permet de simplement générer des visites régulières sur les différents sites et éviter que les tâches des sites peu visités soient trop (...)

  • Ecrire une actualité

    21 juin 2013, par

    Présentez les changements dans votre MédiaSPIP ou les actualités de vos projets sur votre MédiaSPIP grâce à la rubrique actualités.
    Dans le thème par défaut spipeo de MédiaSPIP, les actualités sont affichées en bas de la page principale sous les éditoriaux.
    Vous pouvez personnaliser le formulaire de création d’une actualité.
    Formulaire de création d’une actualité Dans le cas d’un document de type actualité, les champs proposés par défaut sont : Date de publication ( personnaliser la date de publication ) (...)

Sur d’autres sites (4968)

  • Remove references to the "ff" variant of buffersink.

    11 mars 2013, par Nicolas George

    Remove references to the "ff" variant of buffersink.

  • Error in video streaming using libavformat : VBV buffer size not set, muxing may fail

    18 octobre 2017, par Blue Sky

    I stream a video using libavformat as follows :

    static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec,
    
                        enum AVCodecID codec_id)
    
{
    
AVCodecContext *c;
    
AVStream *st;
    
/* find the encoder */
    
*codec = avcodec_find_encoder(codec_id);
    
if (!(*codec)) {
    
    fprintf(stderr, "Could not find encoder for '%s'\n",
    
            avcodec_get_name(codec_id));
    
    exit(1);
    
}
    
st = avformat_new_stream(oc, *codec);
    
if (!st) {
    
    fprintf(stderr, "Could not allocate stream\n");
    
    exit(1);
    
}
    
st->id = oc->nb_streams-1;
    
c = st->codec;
    
switch ((*codec)->type) {
    
case AVMEDIA_TYPE_AUDIO:
    
    c->sample_fmt  = (*codec)->sample_fmts ?
    
        (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;
    
    c->bit_rate    = 64000;
    
    c->sample_rate = 44100;
    
    c->channels    = 2;
    
    break;
    
case AVMEDIA_TYPE_VIDEO:
    
    c->codec_id = codec_id;
    
    c->bit_rate = 400000;
    
    /* Resolution must be a multiple of two. */
    
    c->width    = outframe_width;
    
    c->height   = outframe_height;
    
    /* timebase: This is the fundamental unit of time (in seconds) in terms
    
     * of which frame timestamps are represented. For fixed-fps content,
    
     * timebase should be 1/framerate and timestamp increments should be
    
     * identical to 1. */
    
    c->time_base.den = STREAM_FRAME_RATE;
    
    c->time_base.num = 1;
    
    c->gop_size      = 12; /* emit one intra frame every twelve frames at most */
    
    c->pix_fmt       = STREAM_PIX_FMT;
    
    if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
    
        /* just for testing, we also add B frames */
    
        c->max_b_frames = 2;
    
    }
    
    if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
    
        /* Needed to avoid using macroblocks in which some coeffs overflow.
    
         * This does not happen with normal video, it just happens here as
    
         * the motion of the chroma plane does not match the luma plane. */
    
        c->mb_decision = 2;
    
    }
    
break;
    
default:
    
    break;
    
}
    
/* Some formats want stream headers to be separate. */
    
if (oc->oformat->flags & AVFMT_GLOBALHEADER)
    
    c->flags |= CODEC_FLAG_GLOBAL_HEADER;
    
return st;
    
}

    But when I run this code, I get the following error/warning :

    [mpeg @ 01f3f040] VBV buffer size not set, muxing may fail

    Do you know how I can set the VBV buffer size in the code ? In fact, when I use ffplay to display the streamed video, ffplay doesn’t show anything for short videos but for long videos, it start displaying the video immediately. So, it looks like ffplay needs a buffer to be filled up by some amount so that it can start displaying the stream. Am I right ?

  • Error in video streaming using libavformat : VBV buffer size not set, muxing may fail

    15 janvier 2014, par Blue Sky

    I stream a video using libavformat as follows :

    static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec,
    
                        enum AVCodecID codec_id)
    
{
    
AVCodecContext *c;
    
AVStream *st;
    
/* find the encoder */
    
*codec = avcodec_find_encoder(codec_id);
    
if (!(*codec)) {
    
    fprintf(stderr, "Could not find encoder for '%s'\n",
    
            avcodec_get_name(codec_id));
    
    exit(1);
    
}
    
st = avformat_new_stream(oc, *codec);
    
if (!st) {
    
    fprintf(stderr, "Could not allocate stream\n");
    
    exit(1);
    
}
    
st->id = oc->nb_streams-1;
    
c = st->codec;
    
switch ((*codec)->type) {
    
case AVMEDIA_TYPE_AUDIO:
    
    c->sample_fmt  = (*codec)->sample_fmts ?
    
        (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;
    
    c->bit_rate    = 64000;
    
    c->sample_rate = 44100;
    
    c->channels    = 2;
    
    break;
    
case AVMEDIA_TYPE_VIDEO:
    
    c->codec_id = codec_id;
    
    c->bit_rate = 400000;
    
    /* Resolution must be a multiple of two. */
    
    c->width    = outframe_width;
    
    c->height   = outframe_height;
    
    /* timebase: This is the fundamental unit of time (in seconds) in terms
    
     * of which frame timestamps are represented. For fixed-fps content,
    
     * timebase should be 1/framerate and timestamp increments should be
    
     * identical to 1. */
    
    c->time_base.den = STREAM_FRAME_RATE;
    
    c->time_base.num = 1;
    
    c->gop_size      = 12; /* emit one intra frame every twelve frames at most */
    
    c->pix_fmt       = STREAM_PIX_FMT;
    
    if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
    
        /* just for testing, we also add B frames */
    
        c->max_b_frames = 2;
    
    }
    
    if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
    
        /* Needed to avoid using macroblocks in which some coeffs overflow.
    
         * This does not happen with normal video, it just happens here as
    
         * the motion of the chroma plane does not match the luma plane. */
    
        c->mb_decision = 2;
    
    }
    
break;
    
default:
    
    break;
    
}
    
/* Some formats want stream headers to be separate. */
    
if (oc->oformat->flags & AVFMT_GLOBALHEADER)
    
    c->flags |= CODEC_FLAG_GLOBAL_HEADER;
    
return st;
    
}

    But when I run this code, I get the following error/warning :

    [mpeg @ 01f3f040] VBV buffer size not set, muxing may fail

    Do you know how I can set the VBV buffer size in the code ? In fact, when I use ffplay to display the streamed video, ffplay doesn't show anything for short videos but for long videos, it start displaying the video immediately. So, it looks like ffplay needs a buffer to be filled up by some amount so that it can start displaying the stream. Am I right ?

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