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Chuck D with Fine Arts Militia - No Meaning No
15 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Paul Westerberg - Looking Up in Heaven
15 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Dan the Automator - Relaxation Spa Treatment
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Mis à jour : Septembre 2011
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Gilberto Gil - Oslodum
15 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
Autres articles (42)
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Websites made with MediaSPIP
2 mai 2011, parThis page lists some websites based on MediaSPIP.
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Creating farms of unique websites
13 avril 2011, parMediaSPIP platforms can be installed as a farm, with a single "core" hosted on a dedicated server and used by multiple websites.
This allows (among other things) : implementation costs to be shared between several different projects / individuals rapid deployment of multiple unique sites creation of groups of like-minded sites, making it possible to browse media in a more controlled and selective environment than the major "open" (...) -
Other interesting software
13 avril 2011, parWe don’t claim to be the only ones doing what we do ... and especially not to assert claims to be the best either ... What we do, we just try to do it well and getting better ...
The following list represents softwares that tend to be more or less as MediaSPIP or that MediaSPIP tries more or less to do the same, whatever ...
We don’t know them, we didn’t try them, but you can take a peek.
Videopress
Website : http://videopress.com/
License : GNU/GPL v2
Source code : (...)
Sur d’autres sites (7020)
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libavformat/libavcodec : Why am I getting a significantly shorter video than expected ?
2 mars 2023, par itzjackyscodeThe MVE below is a simple test program that should encode 6 s (360 frames) of video. When I import the exported video (
output.mkv) into a video editor, I see that it is only a fraction of a second. Why is this ? How do I fix it ?

MVE


#include <cstddef>
#include <cstdio>
#include <iostream>
extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavutil></libavutil>imgutils.h>
#include <libswscale></libswscale>swscale.h>
}

namespace av {
 // ERROR HANDLING
 // ==============

 class av_category_t final : public std::error_category {
 public:
 inline const char* name() const noexcept override { return "av_category"; }

 inline std::string message(int code) const noexcept override {
 thread_local static char msg_buffer[AV_ERROR_MAX_STRING_SIZE];
 av_strerror(code, msg_buffer, sizeof(msg_buffer));
 return std::string(msg_buffer);
 }
 };

 inline const std::error_category& av_category() {
 static av_category_t result;
 return result;
 }

 // helper function to create a std::system_error.
 inline std::system_error av_error(int code) {
 return std::system_error(code, av_category());
 }

 // Allocate or reallocate buffers in a video frame.
 inline void alloc_video_frame(
 AVFrame* frame, int width, int height, AVPixelFormat pix_fmt
 ) {
 int err;
 if (frame->width != width || frame->height != height || 
 frame->format != pix_fmt || !av_frame_is_writable(frame)) {
 // unref the old data if any
 if (frame->buf[0] != nullptr) {
 av_frame_unref(frame);
 }

 // reset parameters
 frame->width = width;
 frame->height = height;
 frame->format = pix_fmt;

 // reallocate
 if ((err = av_frame_get_buffer(frame, 0)) < 0)
 throw av_error(err);
 }
 }
 inline void alloc_video_frame(AVFrame* frame, const AVCodecContext* ctx) {
 alloc_video_frame(frame, ctx->width, ctx->height, ctx->pix_fmt);
 }
} // namespace av

void fill_rgb(AVFrame* tmp, AVFrame* dst, uint32_t col) {
 static SwsContext* sws = nullptr;
 int err;
 
 av::alloc_video_frame(tmp, dst->width, dst->height, AV_PIX_FMT_0RGB32);
 for (int i = 0; i < tmp->height; i++) {
 for (int j = 0; j < tmp->width; j++) {
 void* p = tmp->data[0] + (i * tmp->linesize[0]) + (j * 4);
 *((uint32_t*) p) = col;
 }
 }
 
 sws = sws_getCachedContext(sws,
 // src params
 tmp->width, tmp->height, (AVPixelFormat) tmp->format,
 // dst params
 dst->width, dst->height, (AVPixelFormat) dst->format,
 // stuff
 0, nullptr, nullptr, nullptr
 );
 if ((err = sws_scale_frame(sws, dst, tmp)) < 0)
 throw av::av_error(err);
}

int32_t hue_c(int deg) {
 deg %= 360;
 int rem = deg % 60;
 switch (deg / 60) {
 case 0: return 0xFF0000 | ((deg * 256 / 60) << 8);
 case 1: return 0x00FF00 | (((60 - deg) * 256 / 60) << 16);
 case 2: return 0x00FF00 | ((deg * 256 / 60) << 0);
 case 3: return 0x0000FF | (((60 - deg) * 256 / 60) << 8);
 case 4: return 0x00FF00 | ((deg * 256 / 60) << 16);
 case 5: return 0xFF0000 | (((60 - deg) * 256 / 60) << 0);
 }
 return 0xFFFFFF;
}

int main() {
 int res;

 AVFormatContext* fmt_ctx;
 AVStream* vstream;
 const AVCodec* vcodec;
 AVCodecContext* vcodec_ctx;

 AVFrame* vframe;
 AVFrame* vframe2;
 AVPacket* vpacket;

 int64_t pts = 0;

 // init frame
 res = avformat_alloc_output_context2(&fmt_ctx, NULL, NULL, "output.mkv");
 if (res < 0)
 return 1;

 // get encoder
 vcodec = avcodec_find_encoder(AV_CODEC_ID_VP8);

 // allocate everything else
 vstream = avformat_new_stream(fmt_ctx, vcodec);
 vcodec_ctx = avcodec_alloc_context3(vcodec);
 vframe = av_frame_alloc();
 vframe2 = av_frame_alloc();
 vpacket = av_packet_alloc();
 if (!vstream || !vcodec_ctx || !vframe || !vpacket) {
 return 1;
 }

 // set PTS counter
 pts = 0;

 // codec: size parameters
 vcodec_ctx->width = 640;
 vcodec_ctx->height = 480;
 vcodec_ctx->sample_aspect_ratio = {1, 1};

 // codec: pixel formats
 vcodec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;

 // codec: bit rate et al.
 vcodec_ctx->bit_rate = 2e6;
 vcodec_ctx->rc_buffer_size = 4e6;
 vcodec_ctx->rc_max_rate = 2e6;
 vcodec_ctx->rc_min_rate = 2.5e6;

 // codec: frame rate
 vcodec_ctx->time_base = {1, 60};
 vstream->time_base = {1, 60};
 vstream->avg_frame_rate = {60, 1};

 // open codec
 res = avcodec_open2(vcodec_ctx, vcodec, NULL);
 if (res < 0)
 throw av::av_error(res);
 res = avcodec_parameters_from_context(vstream->codecpar, vcodec_ctx);
 if (res < 0)
 throw av::av_error(res);
 
 // open file
 if (!(fmt_ctx->oformat->flags & AVFMT_NOFILE)) {
 res = avio_open(&fmt_ctx->pb, "output.mkv", AVIO_FLAG_WRITE);
 if (res < 0)
 throw av::av_error(res);
 }
 
 // write format header
 res = avformat_write_header(fmt_ctx, NULL);
 if (res < 0)
 throw av::av_error(res);

 // encode loop
 for (int i = 0; i < 360; i++) {
 av::alloc_video_frame(vframe, vcodec_ctx);

 // gen data and store to vframe
 fill_rgb(vframe2, vframe, hue_c(i));
 
 // set timing info
 vframe->time_base = vcodec_ctx->time_base;
 vframe->pts = i;

 // send to encoder
 avcodec_send_frame(vcodec_ctx, vframe);
 while ((res = avcodec_receive_packet(vcodec_ctx, vpacket)) == 0) {
 printf("DTS: %ld, PTS: %ld\n", vpacket->dts, vpacket->pts);
 
 if ((res = av_interleaved_write_frame(fmt_ctx, vpacket)) < 0)
 throw av::av_error(res);
 
 }
 if (res != AVERROR_EOF && res != AVERROR(EAGAIN))
 return -1;
 }
 
 if ((res = av_write_trailer(fmt_ctx)) < 0)
 throw av::av_error(res);
 
 av_frame_free(&vframe);
 av_frame_free(&vframe2);
 av_packet_free(&vpacket);
 avcodec_free_context(&vcodec_ctx);
 
 avformat_free_context(fmt_ctx);
}
</iostream></cstdio></cstddef>

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How to get 1 frame per second in ffmpeg video to images ? Getting more images than expected
15 septembre 2021, par code0x00I am trying to extract images from a video 1 frame per second but i am getting more images than i expect.


for eg. :


When i run below command :


ffmpeg -i filename.mp4 -r 1 img%d.jpg


It is a 20 second video but creating 22 images.


it should create 21 images.


Why it is creating one extra image ?


-
avplay : Always free opts
14 octobre 2014, par Luca Barbato
Syndiquer tout le site
