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Collections - Formulaire de création rapide
19 février 2013, par
Mis à jour : Février 2013
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Ne pas afficher certaines informations : page d’accueil
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Richard Stallman et la révolution du logiciel libre - Une biographie autorisée (version epub)
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Rennes Emotion Map 2010-11
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Autres articles (76)
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MediaSPIP v0.2
21 juin 2013, parMediaSPIP 0.2 est la première version de MediaSPIP stable.
Sa date de sortie officielle est le 21 juin 2013 et est annoncée ici.
Le fichier zip ici présent contient uniquement les sources de MediaSPIP en version standalone.
Comme pour la version précédente, il est nécessaire d’installer manuellement l’ensemble des dépendances logicielles sur le serveur.
Si vous souhaitez utiliser cette archive pour une installation en mode ferme, il vous faudra également procéder à d’autres modifications (...) -
XMP PHP
13 mai 2011, parDixit Wikipedia, XMP signifie :
Extensible Metadata Platform ou XMP est un format de métadonnées basé sur XML utilisé dans les applications PDF, de photographie et de graphisme. Il a été lancé par Adobe Systems en avril 2001 en étant intégré à la version 5.0 d’Adobe Acrobat.
Étant basé sur XML, il gère un ensemble de tags dynamiques pour l’utilisation dans le cadre du Web sémantique.
XMP permet d’enregistrer sous forme d’un document XML des informations relatives à un fichier : titre, auteur, historique (...) -
Use, discuss, criticize
13 avril 2011, parTalk 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 (11554)
-
How to write NALs produced by x264_encoder_encode() using ffmpeg av_interleaved_write_frame()
21 janvier 2013, par Haleeq UsmanI 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 UsmanI 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 !
-
VeriSilicon and WebM Support
24 janvier 2011, par noreply@blogger.com (John Luther)Guest blogger Tomi Jalonen is Director of Product Marketing for Hantro video IP at VeriSilicon
2011 is shaping up to be an exciting year at VeriSilicon Holdings in terms of WebM support. With the new year upon us, I want to share some updates about the work we are doing at VeriSilicon to move the WebM platform forward.
VeriSilicon has been a longtime partner of On2/Hantro (Hantro is the video IP brand that Google acquired with On2 Technologies) and we were among the first hardware partners to commit to WebM video when the codec was open-sourced last year. After promoting WebM to the semiconductor industry during 2010, we’re excited that at CES 2011 the first tablet supporting WebM with full 1080p resolution was demonstrated. VeriSilicon licensed the WebM IP to this tablet manufacturer and provided engineering support to bring the technology to the showroom floor.
In addition to licensing IPs, this year we’ll be taking the WebM experience a step further by taping out several application processor chips—including the WebM video IP for Android phones, xPad, and Google TV—to accelerate the deployment of WebM and HTML5 video playback into the market.
The entire VeriSilicon team is very excited about the future of WebM. We believe that the availability of high-quality, optimized WebM hardware video IP, combined with other VeriSilicon audio and multimedia IP, will be a key ingredient for semiconductor companies to create competitive consumer products. After the launch of WebM, the interest in hardware-accelerated WebM video has been immense and we will continue working with the WebM Project to enable WebM and VP8 in many more chips in 2011.
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