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The pirate bay depuis la Belgique
1er avril 2013, par
Mis à jour : Avril 2013
Langue : français
Type : Image
Autres articles (75)
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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.
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Sur d’autres sites (8704)
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use ffmpeg encode a video in android
18 août 2014, par user2098010i followed below link for using ffmpeg in android
http://www.roman10.net/how-to-build-ffmpeg-with-ndk-r9/and done ! ndk-build
i need to encode a video captured by phone camera for slow down
i’ve using sample file in ffmpeg/sample...
but i can’t get encoded a video(slow down)output video has 1sec playtime.
few color are displayed !plz... help me
i wanna sleep well...
AVCodec *codec;
AVCodecContext *c= NULL;
int i, ret, x, y, got_output;
FILE *f;
AVFrame *frame;
AVPacket pkt;
uint8_t endcode[] = { 0, 0, 1, 0xb7 };
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "%s",filename);
/* find the mpeg1 video encoder */
codec = avcodec_find_encoder(CODEC_ID_H263);
if (!codec) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Codec not found");
exit(1);
}
c = avcodec_alloc_context3(codec);
if (!c) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Could not allocate video codec context");
exit(1);
}
/* put sample parameters */
c->bit_rate = 400000;
/* resolution must be a multiple of two */
c->width = 352;
c->height = 288;
/* frames per second */
c->time_base= (AVRational){1,25};
c->gop_size = 10; /* emit one intra frame every ten frames */
c->pix_fmt = AV_PIX_FMT_YUV420P;
// if(codec == AV_CODEC_ID_H264)
// av_opt_set(c->priv_data, "preset", "slow", 0);
/* open it */
if (avcodec_open2(c, codec, NULL) < 0) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Could not open codec");
exit(1);
}
f = fopen(filename, "wb");
if (f == NULL) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Could not open");
exit(1);
}
frame = avcodec_alloc_frame();
if (!frame) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Could not allocate video frame");
exit(1);
}
frame->format = c->pix_fmt;
frame->width = c->width;
frame->height = c->height;
/* the image can be allocated by any means and av_image_alloc() is
* just the most convenient way if av_malloc() is to be used */
ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
c->pix_fmt, 32);
if (ret < 0) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Could not allocate raw picture buffer");
exit(1);
}
/* encode 1 second of video */
for(i=0;i<250;i++) {
av_init_packet(&pkt);
pkt.data = NULL; // packet data will be allocated by the encoder
pkt.size = 0;
fflush(stdout);
/* prepare a dummy image */
/* Y */
for(y=0;yheight;y++) {
for(x=0;xwidth;x++) {
frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
}
}
/* Cb and Cr */
for(y=0;yheight/2;y++) {
for(x=0;xwidth/2;x++) {
frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
}
}
frame->pts = i;
/* encode the image */
ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
if (ret < 0) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Error encoding frame");
exit(1);
}
if (got_output) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "encode the image Write frame pktsize %d", pkt.size);
fwrite(pkt.data, 1, pkt.size, f);
av_free_packet(&pkt);
}
}
/* get the delayed frames */
for (got_output = 1; got_output; i++) {
fflush(stdout);
ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
if (ret < 0) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "Error encoding frame");
fprintf(stderr, "Error encoding frame\n");
exit(1);
}
if (got_output) {
__android_log_print(ANDROID_LOG_DEBUG, "BASEBALL", "get the delayed frames Write frame pktsize %d", pkt.size);
fwrite(pkt.data, 1, pkt.size, f);
av_free_packet(&pkt);
}
}
/* add sequence end code to have a real mpeg file */
fwrite(endcode, 1, sizeof(endcode), f);
fclose(f);
avcodec_close(c);
av_free(c);
av_freep(&frame->data[0]);
avcodec_free_frame(&frame); -
FFMPEG avformat_write_header changing my stream time_base
24 avril 2015, par cesarpachonI am muxing video using ffmpeg 2.1.3 with libavcodec 55.39.101 (forced to that version because is the one available in google-chrome PNACL port project). all my frames seems to have bad the time. they try to be rendered all at once at the beggining of the video when playing it.
I am setting the stream time base to 1/25, but just after calling avformat_write_header, it has the value of -18082736/1.
in each frame, when I print the stream time_base it says 1/12800, while the time_base of codec is always ok (1/25).console log before and after av_format_write_header :
before avformat_write_header stream time_base: 1/25
after avformat_write_header ret 0 stream time_base: -18082736/1the code (abreviated to keep the post short, all calls in the original version had error checking) :
AVCodecContext *codecContext;
AVCodec * codec = avcodec_find_encoder(codec_id);
myOutputStream->stream = avformat_new_stream(outputFormatContext, *codec);
myOutputStream->stream->id = outputFormatContext->nb_streams-1;
codecContext = myOutputStream->stream->codec;
codecContext->codec_id = codec_id;
codecContext->bit_rate = 400000;
codecContext->width = width;
codecContext->height = height;
myOutputStream->stream->time_base = (AVRational){ 1, 25 };
codecContext->time_base = myOutputStream->stream->time_base;
codecContext->gop_size = 12;
codecContext->pix_fmt = AV_PIX_FMT_YUV420P;
AVDictionary *opt = NULL;
av_dict_copy(&opt, opt_arg, 0);
ret = avcodec_open2(codecContext, codec, &opt);
av_dict_free(&opt);
myOutputStream->frame = alloc_picture(codecContext->pix_fmt, codecContext->width, codecContext->height);
myOutputStream->tmp_frame = alloc_picture(AV_PIX_FMT_YUV420P, codecContext->width, codecContext->height);
//before: printing g_outputContext->stream time_base here
ret = avformat_write_header(g_outputContext, &opt);
//after: printing g_outputContext->stream time_base hereIf I run ffmpeg -i on the final video, I got this (why duration is zero ?) :
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test4.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2mp41
encoder : Lavf55.19.104
Duration: 00:00:00.05, start: 0.000000, bitrate: 99549 kb/s
Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 800x600 [SAR 1:1 DAR 4:3], 463106 kb/s, 12800 fps, 12800 tbr, 12800 tbn, 25 tbc (default)
Metadata:
handler_name : VideoHandler -
Decoding then re-encoding frames in reverse order with ffmpeg
21 août 2014, par user3875919I am pretty new to ffmpeg, and now I want to decode the frames and encode it back in reverse order. I have used this tutorial for decoding the video and this example to encode it back. I can decode the frames properly, but when I re-encode it, I get a dummy image rather than clear video. How can I get the actual reversed video ?
static void video_encode_example(const char *filename, int codec_id)
{
AVCodec *codec;
AVCodecContext *c= NULL;
int i, ret, x, y, got_output;
FILE *f;
struct SwsContext *sws_ctx = NULL;
AVFrame *frame;
AVFrame *frameRGB = NULL;
AVPacket pkt;
uint8_t endcode[] = { 0, 0, 1, 0xb7 };
printf("Encode video file %s\n", filename);
/* find the mpeg1 video encoder */
codec = avcodec_find_encoder(codec_id);
if (!codec) {
fprintf(stderr, "Codec not found\n");
exit(1);
}
c = avcodec_alloc_context3(codec);
if (!c) {
fprintf(stderr, "Could not allocate video codec context\n");
exit(1);
}
/* put sample parameters */
c->bit_rate = 400000;
/* resolution must be a multiple of two */
c->width = 352;
c->height = 288;
/* frames per second */
c->time_base = (AVRational){1,25};
/* emit one intra frame every ten frames
* check frame pict_type before passing frame
* to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
* then gop_size is ignored and the output of encoder
* will always be I frame irrespective to gop_size
*/
c->gop_size = 10;
c->max_b_frames = 1;
c->pix_fmt = AV_PIX_FMT_YUV420P;
if (codec_id == AV_CODEC_ID_H264)
av_opt_set(c->priv_data, "preset", "slow", 0);
/* open it */
if (avcodec_open2(c, codec, NULL) < 0) {
fprintf(stderr, "Could not open codec\n");
exit(1);
}
f = fopen(filename, "wb");
if (!f) {
fprintf(stderr, "Could not open %s\n", filename);
exit(1);
}
frame = av_frame_alloc();
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
frame->format = c->pix_fmt;
frame->width = c->width;
frame->height = c->height;
/* the image can be allocated by any means and av_image_alloc() is
* just the most convenient way if av_malloc() is to be used */
ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
c->pix_fmt, 32);
if (ret < 0) {
fprintf(stderr, "Could not allocate raw picture buffer\n");
exit(1);
}
/* encode 1 second of video */
for (i = 0; i < 25; i++) {
av_init_packet(&pkt);
pkt.data = NULL; // packet data will be allocated by the encoder
pkt.size = 0;
fflush(stdout);
/* prepare a dummy image */
/* Y */
for (y = 0; y < c->height; y++) {
for (x = 0; x < c->width; x++) {
frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
}
}
/* Cb and Cr */
for (y = 0; y < c->height/2; y++) {
for (x = 0; x < c->width/2; x++) {
frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
}
}
frame->pts = i;
/* encode the image */
ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
if (ret < 0) {
fprintf(stderr, "Error encoding frame\n");
exit(1);
}
if (got_output) {
// Convert the image from its native format to RGB
sws_scale
(
sws_ctx,
(uint8_t const * const *)frame->data,
frame->linesize,
0,
c->height,
frameRGB->data,
frameRGB->linesize
);
printf("Write frame %3d (size=%5d)\n", i, pkt.size);
fwrite(pkt.data, 1, pkt.size, f);
av_free_packet(&pkt);
}
}
/* get the delayed frames */
for (got_output = 1; got_output; i++) {
fflush(stdout);
ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
if (ret < 0) {
fprintf(stderr, "Error encoding frame\n");
exit(1);
}
if (got_output) {
printf("Write frame %3d (size=%5d)\n", i, pkt.size);
fwrite(pkt.data, 1, pkt.size, f);
av_free_packet(&pkt);
}
}
/* add sequence end code to have a real mpeg file */
fwrite(endcode, 1, sizeof(endcode), f);
fclose(f);
avcodec_close(c);
av_free(c);
av_freep(&frame->data[0]);
av_frame_free(&frame);
printf("\n");
}
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