Recherche avancée

Médias (2)

Mot : - Tags -/documentation

Autres articles (82)

  • Les vidéos

    21 avril 2011, par

    Comme les documents de type "audio", Mediaspip affiche dans la mesure du possible les vidéos grâce à la balise html5 .
    Un des inconvénients de cette balise est qu’elle n’est pas reconnue correctement par certains navigateurs (Internet Explorer pour ne pas le nommer) et que chaque navigateur ne gère en natif que certains formats de vidéos.
    Son avantage principal quant à lui est de bénéficier de la prise en charge native de vidéos dans les navigateur et donc de se passer de l’utilisation de Flash et (...)

  • Gestion des droits de création et d’édition des objets

    8 février 2011, par

    Par défaut, beaucoup de fonctionnalités sont limitées aux administrateurs mais restent configurables indépendamment pour modifier leur statut minimal d’utilisation notamment : la rédaction de contenus sur le site modifiables dans la gestion des templates de formulaires ; l’ajout de notes aux articles ; l’ajout de légendes et d’annotations sur les images ;

  • Le profil des utilisateurs

    12 avril 2011, par

    Chaque utilisateur dispose d’une page de profil lui permettant de modifier ses informations personnelle. Dans le menu de haut de page par défaut, un élément de menu est automatiquement créé à l’initialisation de MediaSPIP, visible uniquement si le visiteur est identifié sur le site.
    L’utilisateur a accès à la modification de profil depuis sa page auteur, un lien dans la navigation "Modifier votre profil" est (...)

Sur d’autres sites (8528)

  • How to write NALs produced by x264_encoder_encode() using ffmpeg av_interleaved_write_frame()

    21 janvier 2013, par Haleeq Usman

    I have been trying to produce a "flv" video file in the following sequence :

    av_register_all();
    

    
// Open video file
    
if (avformat_open_input(&pFormatCtx, "6.mp4", NULL, NULL) != 0)
    
    return -1; // Couldn't open file
    

    
// Retrieve stream information
    
if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
    
    return -1; // Couldn't find stream information
    

    
// Dump information about file onto standard error
    
av_dump_format(pFormatCtx, 0, "input_file.mp4", 0);
    

    
// Find the first video stream
    
videoStream = -1;
    
for (i = 0; i < pFormatCtx->nb_streams; i++)
    
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
    
        videoStream = i;
    
        break;
    
    }
    
if (videoStream == -1)
    
    return -1; // Didn't find a video stream
    

    
// Get a pointer to the codec context for the video stream
    
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
    

    
// Find the decoder for the video stream
    
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
    
if (pCodec == NULL) {
    
    fprintf(stderr, "Unsupported codec!\n");
    
    return -1; // Codec not found
    
}
    
// Open codec
    
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
    
    return -1; // Could not open codec
    

    
// Allocate video frame
    
pFrame = avcodec_alloc_frame();
    

    
// Allocate video frame
    
pFrame = avcodec_alloc_frame();
    

    
// Allocate an AVFrame structure
    
pFrameYUV420 = avcodec_alloc_frame();
    
if (pFrameYUV420 == NULL)
    
    return -1;
    

    
// Determine required buffer size and allocate buffer
    
numBytes = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
    
buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
    

    
// Assign appropriate parts of buffer to image planes in pFrameYUV420
    
// Note that pFrameYUV420 is an AVFrame, but AVFrame is a superset of AVPicture
    
avpicture_fill((AVPicture *) pFrameRGB, buffer, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
    

    
// Setup scaler
    
img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, SWS_BILINEAR, 0, 0, 0);
    
if (img_convert_ctx == NULL) {
    
    fprintf(stderr, "Cannot initialize the conversion context!\n");
    
    exit(1);
    
}
    

    
// Setup encoder/muxing now
    
filename = "output_file.flv";
    
fmt = av_guess_format("flv", filename, NULL);
    
if (fmt == NULL) {
    
    printf("Could not guess format.\n");
    
    return -1;
    
}
    
/* allocate the output media context */
    
oc = avformat_alloc_context();
    
if (oc == NULL) {
    
    printf("could not allocate context.\n");
    
    return -1;
    
}
    
oc->oformat = fmt;
    
snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
    

    
video_st = NULL;
    
if (fmt->video_codec != AV_CODEC_ID_NONE) {
    
    video_st = add_stream(oc, &video_codec, fmt->video_codec);
    
}
    

    
// Let's see some information about our format
    
av_dump_format(oc, 0, filename, 1);
    

    
/* open the output file, if needed */
    
if (!(fmt->flags & AVFMT_NOFILE)) {
    
    ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
    
    if (ret < 0) {
    
        fprintf(stderr, "Could not open '%s': %s\n", filename, av_err2str(ret));
    
        return 1;
    
    }
    
    }
    
/* Write the stream header, if any. */
    
ret = avformat_write_header(oc, NULL);
    
if (ret < 0) {
    
    fprintf(stderr, "Error occurred when opening output file: %s\n", av_err2str(ret));
    
    return 1;
    
}
    

    
// Setup x264 params
    
x264_param_t param;
    
x264_param_default_preset(&param, "veryfast", "zerolatency");
    
param.i_threads = 1;
    
param.i_width = video_st->codec->width;
    
param.i_height = video_st->codec->height;
    
param.i_fps_num = STREAM_FRAME_RATE; // 30 fps, same as video
    
param.i_fps_den = 1;
    
// Intra refres:
    
param.i_keyint_max = STREAM_FRAME_RATE;
    
param.b_intra_refresh = 1;
    
// Rate control:
    
param.rc.i_rc_method = X264_RC_CRF;
    
param.rc.f_rf_constant = 25;
    
param.rc.f_rf_constant_max = 35;
    
// For streaming:
    
param.b_repeat_headers = 1;
    
param.b_annexb = 1;
    
x264_param_apply_profile(&param, "baseline");
    

    
x264_t* encoder = x264_encoder_open(&param);
    
x264_picture_t pic_in, pic_out;
    
x264_picture_alloc(&pic_in, X264_CSP_I420, video_st->codec->width, video_st->codec->height);
    

    
x264_nal_t* nals;
    
int i_nals;
    

    
// The loop:
    
// 1. Read frames
    
// 2. Decode the frame
    
// 3. Attempt to re-encode using x264
    
// 4. Write the x264 encoded frame using av_interleaved_write_frame
    
while (av_read_frame(pFormatCtx, &packet) >= 0) {
    
    // Is this a packet from the video stream?
    
    if (packet.stream_index == videoStream) {
    
        // Decode video frame
    
        avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
    

    
        // Did we get a video frame?
    
        if (frameFinished) {
    
            sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pic_in.img.plane, pic_in.img.i_stride);
    
            int frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);
    

    
            if (frame_size >= 0) {
    
                if (i_nals < 0)
    
                    printf("invalid frame size: %d\n", i_nals);
    
                // write out NALs
    
                for (i = 0; i < i_nals; i++) {
    
                    // initalize a packet
    
                    AVPacket p;
    
                    av_init_packet(&p);
    
                    p.data = nals[i].p_payload;
    
                    p.size = nals[i].i_payload;
    
                    p.stream_index = video_st->index;
    
                    p.flags = AV_PKT_FLAG_KEY;
    
                    p.pts = AV_NOPTS_VALUE;
    
                    p.dts = AV_NOPTS_VALUE;
    
                    ret = av_interleaved_write_frame(oc, &p);
    
                }
    
            }
    
            printf("encoded frame #%d\n", frame_count);
    
            frame_count++;
    
        }
    
    }
    

    
    // Free the packet that was allocated by av_read_frame
    
    av_free_packet(&packet);
    
}
    

    
// Now we free up resources used/close codecs, and finally close our program.

    Here is the implementation for the add_stream() function :

    /* Add an output stream. */
    
static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id) {
    
    AVCodecContext *c;
    
    AVStream *st;
    
    int r;
    
    /* 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:
    
        st->id = 1;
    
        c->sample_fmt = AV_SAMPLE_FMT_FLTP;
    
        c->bit_rate = 64000;
    
        c->sample_rate = 44100;
    
        c->channels = 2;
    
        break;
    
    case AVMEDIA_TYPE_VIDEO:
    
        avcodec_get_context_defaults3(c, *codec);
    
        c->codec_id = codec_id;
    
        c->bit_rate = 500*1000;
    
        //c->rc_min_rate = 500*1000;
    
        //c->rc_max_rate = 500*1000;
    
        //c->rc_buffer_size = 500*1000;
    
        /* Resolution must be a multiple of two. */
    
        c->width = 1280;
    
        c->height = 720;
    
        /* 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;
    
}

    After the encoding is complete, I check the output file output_file.flv. I notice it's size is very large : 101MB and it does not play. If I use ffmpeg to decode/encode the input file, then I get an output file about 83MB in size (which is about the same size as the original .mp4 file used as input). Also, the 83MB output from just using ffmpeg C api, as opposed to using x264 for the encoding step, plays just fine. Does anyone know where I am going wrong ? I have tried researching this for a few days now but with no luck :(. I feel that I am close to making it work, however, I just cannot figure out what I am doing wrong. Thank you !

  • How to write NALs produced by x264_encoder_encode() using ffmpeg av_interleaved_write_frame()

    21 janvier 2013, par Haleeq Usman

    I have been trying to produce a "flv" video file in the following sequence :

    av_register_all();
    

    
// Open video file
    
if (avformat_open_input(&pFormatCtx, "6.mp4", NULL, NULL) != 0)
    
    return -1; // Couldn't open file
    

    
// Retrieve stream information
    
if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
    
    return -1; // Couldn't find stream information
    

    
// Dump information about file onto standard error
    
av_dump_format(pFormatCtx, 0, "input_file.mp4", 0);
    

    
// Find the first video stream
    
videoStream = -1;
    
for (i = 0; i < pFormatCtx->nb_streams; i++)
    
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
    
        videoStream = i;
    
        break;
    
    }
    
if (videoStream == -1)
    
    return -1; // Didn't find a video stream
    

    
// Get a pointer to the codec context for the video stream
    
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
    

    
// Find the decoder for the video stream
    
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
    
if (pCodec == NULL) {
    
    fprintf(stderr, "Unsupported codec!\n");
    
    return -1; // Codec not found
    
}
    
// Open codec
    
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
    
    return -1; // Could not open codec
    

    
// Allocate video frame
    
pFrame = avcodec_alloc_frame();
    

    
// Allocate video frame
    
pFrame = avcodec_alloc_frame();
    

    
// Allocate an AVFrame structure
    
pFrameYUV420 = avcodec_alloc_frame();
    
if (pFrameYUV420 == NULL)
    
    return -1;
    

    
// Determine required buffer size and allocate buffer
    
numBytes = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
    
buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
    

    
// Assign appropriate parts of buffer to image planes in pFrameYUV420
    
// Note that pFrameYUV420 is an AVFrame, but AVFrame is a superset of AVPicture
    
avpicture_fill((AVPicture *) pFrameRGB, buffer, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
    

    
// Setup scaler
    
img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, SWS_BILINEAR, 0, 0, 0);
    
if (img_convert_ctx == NULL) {
    
    fprintf(stderr, "Cannot initialize the conversion context!\n");
    
    exit(1);
    
}
    

    
// Setup encoder/muxing now
    
filename = "output_file.flv";
    
fmt = av_guess_format("flv", filename, NULL);
    
if (fmt == NULL) {
    
    printf("Could not guess format.\n");
    
    return -1;
    
}
    
/* allocate the output media context */
    
oc = avformat_alloc_context();
    
if (oc == NULL) {
    
    printf("could not allocate context.\n");
    
    return -1;
    
}
    
oc->oformat = fmt;
    
snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
    

    
video_st = NULL;
    
if (fmt->video_codec != AV_CODEC_ID_NONE) {
    
    video_st = add_stream(oc, &video_codec, fmt->video_codec);
    
}
    

    
// Let's see some information about our format
    
av_dump_format(oc, 0, filename, 1);
    

    
/* open the output file, if needed */
    
if (!(fmt->flags & AVFMT_NOFILE)) {
    
    ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
    
    if (ret < 0) {
    
        fprintf(stderr, "Could not open '%s': %s\n", filename, av_err2str(ret));
    
        return 1;
    
    }
    
    }
    
/* Write the stream header, if any. */
    
ret = avformat_write_header(oc, NULL);
    
if (ret < 0) {
    
    fprintf(stderr, "Error occurred when opening output file: %s\n", av_err2str(ret));
    
    return 1;
    
}
    

    
// Setup x264 params
    
x264_param_t param;
    
x264_param_default_preset(&param, "veryfast", "zerolatency");
    
param.i_threads = 1;
    
param.i_width = video_st->codec->width;
    
param.i_height = video_st->codec->height;
    
param.i_fps_num = STREAM_FRAME_RATE; // 30 fps, same as video
    
param.i_fps_den = 1;
    
// Intra refres:
    
param.i_keyint_max = STREAM_FRAME_RATE;
    
param.b_intra_refresh = 1;
    
// Rate control:
    
param.rc.i_rc_method = X264_RC_CRF;
    
param.rc.f_rf_constant = 25;
    
param.rc.f_rf_constant_max = 35;
    
// For streaming:
    
param.b_repeat_headers = 1;
    
param.b_annexb = 1;
    
x264_param_apply_profile(&param, "baseline");
    

    
x264_t* encoder = x264_encoder_open(&param);
    
x264_picture_t pic_in, pic_out;
    
x264_picture_alloc(&pic_in, X264_CSP_I420, video_st->codec->width, video_st->codec->height);
    

    
x264_nal_t* nals;
    
int i_nals;
    

    
// The loop:
    
// 1. Read frames
    
// 2. Decode the frame
    
// 3. Attempt to re-encode using x264
    
// 4. Write the x264 encoded frame using av_interleaved_write_frame
    
while (av_read_frame(pFormatCtx, &packet) >= 0) {
    
    // Is this a packet from the video stream?
    
    if (packet.stream_index == videoStream) {
    
        // Decode video frame
    
        avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
    

    
        // Did we get a video frame?
    
        if (frameFinished) {
    
            sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pic_in.img.plane, pic_in.img.i_stride);
    
            int frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);
    

    
            if (frame_size >= 0) {
    
                if (i_nals < 0)
    
                    printf("invalid frame size: %d\n", i_nals);
    
                // write out NALs
    
                for (i = 0; i < i_nals; i++) {
    
                    // initalize a packet
    
                    AVPacket p;
    
                    av_init_packet(&p);
    
                    p.data = nals[i].p_payload;
    
                    p.size = nals[i].i_payload;
    
                    p.stream_index = video_st->index;
    
                    p.flags = AV_PKT_FLAG_KEY;
    
                    p.pts = AV_NOPTS_VALUE;
    
                    p.dts = AV_NOPTS_VALUE;
    
                    ret = av_interleaved_write_frame(oc, &p);
    
                }
    
            }
    
            printf("encoded frame #%d\n", frame_count);
    
            frame_count++;
    
        }
    
    }
    

    
    // Free the packet that was allocated by av_read_frame
    
    av_free_packet(&packet);
    
}
    

    
// Now we free up resources used/close codecs, and finally close our program.

    Here is the implementation for the add_stream() function :

    /* Add an output stream. */
    
static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id) {
    
    AVCodecContext *c;
    
    AVStream *st;
    
    int r;
    
    /* 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:
    
        st->id = 1;
    
        c->sample_fmt = AV_SAMPLE_FMT_FLTP;
    
        c->bit_rate = 64000;
    
        c->sample_rate = 44100;
    
        c->channels = 2;
    
        break;
    
    case AVMEDIA_TYPE_VIDEO:
    
        avcodec_get_context_defaults3(c, *codec);
    
        c->codec_id = codec_id;
    
        c->bit_rate = 500*1000;
    
        //c->rc_min_rate = 500*1000;
    
        //c->rc_max_rate = 500*1000;
    
        //c->rc_buffer_size = 500*1000;
    
        /* Resolution must be a multiple of two. */
    
        c->width = 1280;
    
        c->height = 720;
    
        /* 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;
    
}

    After the encoding is complete, I check the output file output_file.flv. I notice it's size is very large : 101MB and it does not play. If I use ffmpeg to decode/encode the input file, then I get an output file about 83MB in size (which is about the same size as the original .mp4 file used as input). Also, the 83MB output from just using ffmpeg C api, as opposed to using x264 for the encoding step, plays just fine. Does anyone know where I am going wrong ? I have tried researching this for a few days now but with no luck :(. I feel that I am close to making it work, however, I just cannot figure out what I am doing wrong. Thank you !

  • Anomalie #2939 : Création/modification d’auteur par un admin restreint

    28 février 2013, par marcimat -

    Note (cy_altern dit que) : Historiquement un admin restreint peut créer des auteurs mais pas leur attribuer un mot de passe du coup il ne sont pas actifs. On avait discuté de cette situation bizare une fois et il me semble que ce qui était ressorti c’est que finalement autant qu’il ne puisse pas (...)

Navigation