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Sur d’autres sites (4888)
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Converting from rawvideo camera bytes to flv using ffmpeg
5 janvier 2023, par Mahmoud AshourI'm trying to convert an android camera stream with pixel format of YUV420 to .flv format in flutter.


-y -f rawvideo -vcodec rawvideo -pix_fmt yuv420p -s 720x480 -i $value -c:v flv $cameraFilePath


Where the value is the input of the raw video data.
However when I see the output it's something like this video


Is there a problem in the color format output , or the input data is corrupted ?


-
FFMPEG crash while cropping video
18 octobre 2022, par Khawar RazaI am using FFMPEG to crop a video. I am using ffmpeg-kit as a ffmpeg wrapper in my android app where the user can select any output size irrespective of the original video aspect ratio. Below is the problematic command :


-i "/storage/emulated/0/Download/83a2f6_1080p~2.mp4" -filter_complex "[0:v]crop=304:236:2:2[cropped]" -map "[cropped]" "/storage/emulated/0/DCIM/appname/vid_d8ee328d-ec7a-468b-9313-4561dceea33e.mp4"


When the execution starts, the application crashes.


Logs :


I/ffmpeg-kit: Loading ffmpeg-kit.
I/ffmpeg-kit: Loaded ffmpeg-kit-min-gpl-arm64-v8a-4.5.1-20220101.
D/ffmpeg-kit: Async callback block started.
D/VideoEditor: ffmpeg version v4.5-dev-3393-g30322ebe3c
D/VideoEditor: Copyright (c) 2000-2021 the FFmpeg developers
D/VideoEditor: 
D/VideoEditor: built with Android (7155654, based on r399163b1) clang version 11.0.5 (https://android.googlesource.com/toolchain/llvm-project 87f1315dfbea7c137aa2e6d362dbb457e388158d)
D/VideoEditor: configuration: --cross-prefix=aarch64-linux-android- --sysroot=/files/android-sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/sysroot --prefix=/storage/light/projects/ffmpeg-kit/prebuilt/android-arm64/ffmpeg --pkg-config=/usr/bin/pkg-config --enable-version3 --arch=aarch64 --cpu=armv8-a --target-os=android --enable-neon --enable-asm --enable-inline-asm --ar=aarch64-linux-android-ar --cc=aarch64-linux-android24-clang --cxx=aarch64-linux-android24-clang++ --ranlib=aarch64-linux-android-ranlib --strip=aarch64-linux-android-strip --nm=aarch64-linux-android-nm --extra-libs='-L/storage/light/projects/ffmpeg-kit/prebuilt/android-arm64/cpu-features/lib -lndk_compat' --disable-autodetect --enable-cross-compile --enable-pic --enable-jni --enable-optimizations --enable-swscale --disable-static --enable-shared --enable-pthreads --enable-v4l2-m2m --disable-outdev=fbdev --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --enable-lto --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --disable-videotoolbox --disable-audiotoolbox --disable-appkit --disable-alsa --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --enable-libx264 --enable-libxvid --enable-libx265 --enable-libvidstab --disable-sdl2 --disable-openssl --enable-zlib --enable-mediacodec --enable-gpl
D/VideoEditor: libavutil 57. 13.100 / 57. 13.100
D/VideoEditor: libavcodec 59. 15.102 / 59. 15.102
D/VideoEditor: libavformat 59. 10.100 / 59. 10.100
D/VideoEditor: libavdevice 59. 1.100 / 59. 1.100
D/VideoEditor: libavfilter 8. 21.100 / 8. 21.100
D/VideoEditor: libswscale 6. 1.102 / 6. 1.102
D/VideoEditor: libswresample 4. 0.100 / 4. 0.100
D/VideoEditor: Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/Download/83a2f6_1080p~2.mp4':
D/VideoEditor: Metadata:
D/VideoEditor: major_brand : 
D/VideoEditor: mp42
D/VideoEditor: 
D/VideoEditor: minor_version : 
D/VideoEditor: 0
D/VideoEditor: 
D/VideoEditor: compatible_brands: 
D/VideoEditor: isommp42
D/VideoEditor: 
D/VideoEditor: com.android.version: 
D/VideoEditor: 12
D/VideoEditor: 
D/VideoEditor: Duration: 
D/VideoEditor: 00:02:18.11
D/VideoEditor: , start: 
D/VideoEditor: 0.000000
D/VideoEditor: , bitrate: 
D/VideoEditor: 1929 kb/s
D/VideoEditor: 
D/VideoEditor: Stream #0:0
D/VideoEditor: [0x1]
D/VideoEditor: (eng)
D/VideoEditor: : Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1080x808, 1864 kb/s
D/VideoEditor: , 
D/VideoEditor: 18 fps, 
D/VideoEditor: 18 tbr, 
D/VideoEditor: 90k tbn
D/VideoEditor: (default)
D/VideoEditor: 
D/VideoEditor: Metadata:
D/VideoEditor: creation_time : 
D/VideoEditor: 2022-10-06T11:47:07.000000Z
D/VideoEditor: 
D/VideoEditor: handler_name : 
D/VideoEditor: VideoHandle
D/VideoEditor: 
D/VideoEditor: vendor_id : 
D/VideoEditor: [0][0][0][0]
D/VideoEditor: 
D/VideoEditor: Stream #0:1
D/VideoEditor: [0x2]
D/VideoEditor: (und)
D/VideoEditor: : Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 64 kb/s
D/VideoEditor: (default)
D/VideoEditor: 
D/VideoEditor: Metadata:
D/VideoEditor: creation_time : 
D/VideoEditor: 2022-10-06T11:47:07.000000Z
D/VideoEditor: 
D/VideoEditor: handler_name : 
D/VideoEditor: SoundHandle
D/VideoEditor: 
D/VideoEditor: vendor_id : 
D/VideoEditor: [0][0][0][0]
D/VideoEditor: 


D/VideoEditor: [h264 @ 0x7654fe8500] The "sub_text_format" option is deprecated: Deprecated, does nothing
D/VideoEditor: Stream mapping:
D/VideoEditor: Stream #0:0 (h264) -> crop
D/VideoEditor: 
D/VideoEditor: crop
D/VideoEditor: -> Stream #0:0 (libx264)
D/VideoEditor: Press [q] to stop, [?] for help


D/VideoEditor: [libx264 @ 0x7654fb9af0] using cpu capabilities: ARMv8 NEON
D/VideoEditor: [libx264 @ 0x7654fb9af0] profile High, level 1.2, 4:2:0, 8-bit
D/VideoEditor: [libx264 @ 0x7654fb9af0] 264 - core 163 - H.264/MPEG-4 AVC codec - Copyleft 2003-2021 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=7 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=18 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
D/VideoEditor: Output #0, mp4, to '/storage/emulated/0/DCIM/appname/vid_d8ee328d-ec7a-468b-9313-4561dceea33e.mp4':
D/VideoEditor: Metadata:
D/VideoEditor: major_brand : 
D/VideoEditor: mp42
D/VideoEditor: 
D/VideoEditor: minor_version : 
D/VideoEditor: 0
D/VideoEditor: 
D/VideoEditor: compatible_brands: 
D/VideoEditor: isommp42
D/VideoEditor: 
D/VideoEditor: com.android.version: 
D/VideoEditor: 12
D/VideoEditor: 
D/VideoEditor: encoder : 
D/VideoEditor: Lavf59.10.100
D/VideoEditor: 
D/VideoEditor: Stream #0:0
D/VideoEditor: : Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 304x236, q=2-31
D/VideoEditor: , 
D/VideoEditor: 18 fps, 
D/VideoEditor: 18432 tbn
D/VideoEditor: (default)
D/VideoEditor: 
D/VideoEditor: Metadata:
D/VideoEditor: encoder : 
D/VideoEditor: Lavc59.15.102 libx264
D/VideoEditor: 
D/VideoEditor: Side data:
D/VideoEditor: 
D/VideoEditor: cpb: 
D/VideoEditor: bitrate max/min/avg: 0/0/0 buffer size: 0 
D/VideoEditor: vbv_delay: N/A
D/VideoEditor: 
D/VideoEditor: frame= 1 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A speed= 0x 

A/libc: Fatal signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0x745d9ff000 in tid 16893 (pool-15-thread-), pid 16696 (videocompressor)


A/DEBUG: *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Build fingerprint: 'samsung/x1sxx/x1s:12/SP1A.210812.016/G980FXXSFFVH7:user/release-keys'
Revision: '22'
ABI: 'arm64'
Processor: '5'
A/DEBUG: Timestamp: 2022-10-09 18:57:38.882598912+0500
A/DEBUG: Process uptime: 1086s
A/DEBUG: Cmdline: com.app.packagename
A/DEBUG: pid: 16939, tid: 20568, name: pool-15-thread- >>> com.app.packagename <<<
A/DEBUG: uid: 11091
A/DEBUG: signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0x74640ce000
A/DEBUG: x0 0000007594f30960 x1 00000074640c9a60 x2 00000074640c9eb4 x3 00000074640cac34
A/DEBUG: x4 00000074640cdff4 x5 00000074671bb2dc x6 00000000fffffffb x7 0000000000000013
A/DEBUG: x8 000000000000000e x9 00000074640cddc0 x10 0000000000000013 x11 0000007488459ffc
A/DEBUG: x12 00000074640c9c70 x13 000000000000000e x14 0000000000007fff x15 0000000000000013
A/DEBUG: x16 00000074640cac04 x17 00000074640c7a58 x18 000000746626e000 x19 0000000000000027
A/DEBUG: x20 000000776541c3b0 x21 00000074671bc4f8 x22 00000074640ca9f0 x23 0000007765422300
A/DEBUG: x24 0000000000000027 x25 00000074640cac04 x26 0000000000000028 x27 00000074640c9a30
A/DEBUG: x28 0000007594f30940 x29 000000000000010a
A/DEBUG: lr 000000748841a960 sp 00000074671bb290 pc 000000748845a010 pst 0000000080000000
A/DEBUG: backtrace:
A/DEBUG: #00 pc 0000000000359010 /data/app/~~IBCbjRbZBpQ00ORNDFZdxg==/com.app.packagename-5sdOCmN82SjJJTibcsYMpQ==/base.apk!libavcodec.so


I don't know what is wrong with the output width and height parameters. If I change
[0:v]crop=304:236:2:2[cropped]to[0:v]crop=304:304:2:2[cropped]with change in height, the process completes successfully. The original video (1080x808) is not smaller than the output size. It does not seem to be a problem in the video as I have tried different videos. Any tips on what is missing from my command ?

-
Getting shifted timestamps when encoding a fragmented h264 mp4 with ffmpeg
14 septembre 2022, par Martin CastinI am trying to encode a fragmented h264 mp4 with ffmpeg. I tried the following command :


ffmpeg -i input.mp4 -movflags +frag_keyframe+separate_moof+omit_tfhd_offset+empty_moov output.mp4


It does give me a fragmented mp4 but the timestamps of the frames seem to be shifted by 0.04s when I read the video with mpv. The first frame has a timestamp of 0.04s instead of 0s, as in the input video (1920x1080, 50 fps). I encountered the problem both with ffmpeg 5.1 and ffmpeg 3.4.11.


I tried to add several flags, as
-avoid_negative_ts make_zeroor-copyts -output_ts_offset -0.04, but it did not help.

I am also trying to achieve this using the ffmpeg libav libraries in C++ but did not get to better result. Here are the code fragments I used.


avformat_alloc_output_context2(&oc, NULL, NULL, filename);

 if (oc_->oformat->flags & AVFMT_GLOBALHEADER) {
 codecCtx_->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
 }
...
 AVDictionary* opts = NULL;

 av_dict_set(&opts, "movflags", "frag_keyframe+separate_moof+omit_tfhd_offset+empty_moov", 0);

 ret = avformat_write_header(oc_, &opts);


Do you know how to avoid this behaviour of shifted timestamps for fragmented mp4, either with ffmpeg or libav ?


Edit : example videos and complete code example


I also tried with the following ffmpeg build


ffmpeg version 5.0.1-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2022 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
libavutil 57. 17.100 / 57. 17.100
libavcodec 59. 18.100 / 59. 18.100
libavformat 59. 16.100 / 59. 16.100
libavdevice 59. 4.100 / 59. 4.100
libavfilter 8. 24.100 / 8. 24.100
libswscale 6. 4.100 / 6. 4.100
libswresample 4. 3.100 / 4. 3.100
libpostproc 56. 3.100 / 56. 3.100


and with the sintel trailer as input video, which is 24fps, and I thus get a timeshift of 83ms. Here is the output I get.


Here is a complete code example, slightly adapted from the
muxing.cffmpeg example (audio removed and adapted for c++). This code shows exactly the same problem.

You can just comment the line 383 (that is calling
av_dict_set) to switch back to a not fragmented mp4 that will not have the timestamp shift.

/*
 * Copyright (c) 2003 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * @file
 * libavformat API example.
 *
 * Output a media file in any supported libavformat format. The default
 * codecs are used.
 * @example muxing.c
 */

#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <cmath>

extern "C"
{
#define __STDC_CONSTANT_MACROS
#include <libavutil></libavutil>avassert.h>
#include <libavutil></libavutil>channel_layout.h>
#include <libavutil></libavutil>opt.h>
#include <libavutil></libavutil>mathematics.h>
#include <libavutil></libavutil>timestamp.h>
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libswscale></libswscale>swscale.h>
#include <libswresample></libswresample>swresample.h>
}

#define STREAM_DURATION 10.0
#define STREAM_FRAME_RATE 25 /* 25 images/s */
#define STREAM_PIX_FMT AV_PIX_FMT_YUV420P /* default pix_fmt */

#define SCALE_FLAGS SWS_BICUBIC

// a wrapper around a single output AVStream
typedef struct OutputStream {
 AVStream *st;
 AVCodecContext *enc;

 /* pts of the next frame that will be generated */
 int64_t next_pts;
 int samples_count;

 AVFrame *frame;
 AVFrame *tmp_frame;

 AVPacket *tmp_pkt;

 float t, tincr, tincr2;

 struct SwsContext *sws_ctx;
 struct SwrContext *swr_ctx;
} OutputStream;

static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
{
 AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;

// printf("pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",
// av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, time_base),
// av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, time_base),
// av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, time_base),
// pkt->stream_index);
}

static int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
 AVStream *st, AVFrame *frame, AVPacket *pkt)
{
 int ret;

 // send the frame to the encoder
 ret = avcodec_send_frame(c, frame);
 if (ret < 0) {
 fprintf(stderr, "Error sending a frame to the encoder");
 exit(1);
 }

 while (ret >= 0) {
 ret = avcodec_receive_packet(c, pkt);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 break;
 else if (ret < 0) {
 fprintf(stderr, "Error encoding a frame\n");
 exit(1);
 }

 /* rescale output packet timestamp values from codec to stream timebase */
 av_packet_rescale_ts(pkt, c->time_base, st->time_base);
 pkt->stream_index = st->index;

 /* Write the compressed frame to the media file. */
 log_packet(fmt_ctx, pkt);
 ret = av_interleaved_write_frame(fmt_ctx, pkt);
 /* pkt is now blank (av_interleaved_write_frame() takes ownership of
 * its contents and resets pkt), so that no unreferencing is necessary.
 * This would be different if one used av_write_frame(). */
 if (ret < 0) {
 fprintf(stderr, "Error while writing output packet\n");
 exit(1);
 }
 }

 return ret == AVERROR_EOF ? 1 : 0;
}

/* Add an output stream. */
static void add_stream(OutputStream *ost, AVFormatContext *oc,
 const AVCodec **codec,
 enum AVCodecID codec_id)
{
 AVCodecContext *c;
 int i;

 /* 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);
 }

 ost->tmp_pkt = av_packet_alloc();
 if (!ost->tmp_pkt) {
 fprintf(stderr, "Could not allocate AVPacket\n");
 exit(1);
 }

 ost->st = avformat_new_stream(oc, NULL);
 if (!ost->st) {
 fprintf(stderr, "Could not allocate stream\n");
 exit(1);
 }
 ost->st->id = oc->nb_streams-1;
 c = avcodec_alloc_context3(*codec);
 if (!c) {
 fprintf(stderr, "Could not alloc an encoding context\n");
 exit(1);
 }
 ost->enc = c;

 switch ((*codec)->type) {
 case AVMEDIA_TYPE_VIDEO:
 c->codec_id = codec_id;

 c->bit_rate = 400000;
 /* Resolution must be a multiple of two. */
 c->width = 352;
 c->height = 288;
 /* 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. */
 ost->st->time_base = (AVRational){ 1, STREAM_FRAME_RATE };
 c->time_base = ost->st->time_base;

 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 |= AV_CODEC_FLAG_GLOBAL_HEADER;
}

/**************************************************************/
/* video output */

static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
{
 AVFrame *picture;
 int ret;

 picture = av_frame_alloc();
 if (!picture)
 return NULL;

 picture->format = pix_fmt;
 picture->width = width;
 picture->height = height;

 /* allocate the buffers for the frame data */
 ret = av_frame_get_buffer(picture, 0);
 if (ret < 0) {
 fprintf(stderr, "Could not allocate frame data.\n");
 exit(1);
 }

 return picture;
}

static void open_video(AVFormatContext *oc, const AVCodec *codec,
 OutputStream *ost, AVDictionary *opt_arg)
{
 int ret;
 AVCodecContext *c = ost->enc;
 AVDictionary *opt = NULL;

 av_dict_copy(&opt, opt_arg, 0);

 /* open the codec */
 ret = avcodec_open2(c, codec, &opt);
 av_dict_free(&opt);
 if (ret < 0) {
 fprintf(stderr, "Could not open video codec\n");
 exit(1);
 }

 /* allocate and init a re-usable frame */
 ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);
 if (!ost->frame) {
 fprintf(stderr, "Could not allocate video frame\n");
 exit(1);
 }

 /* If the output format is not YUV420P, then a temporary YUV420P
 * picture is needed too. It is then converted to the required
 * output format. */
 ost->tmp_frame = NULL;
 if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
 ost->tmp_frame = alloc_picture(AV_PIX_FMT_YUV420P, c->width, c->height);
 if (!ost->tmp_frame) {
 fprintf(stderr, "Could not allocate temporary picture\n");
 exit(1);
 }
 }

 /* copy the stream parameters to the muxer */
 ret = avcodec_parameters_from_context(ost->st->codecpar, c);
 if (ret < 0) {
 fprintf(stderr, "Could not copy the stream parameters\n");
 exit(1);
 }
}

/* Prepare a dummy image. */
static void fill_yuv_image(AVFrame *pict, int frame_index,
 int width, int height)
{
 int x, y, i;

 i = frame_index;

 /* Y */
 for (y = 0; y < height; y++)
 for (x = 0; x < width; x++)
 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;

 /* Cb and Cr */
 for (y = 0; y < height / 2; y++) {
 for (x = 0; x < width / 2; x++) {
 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
 }
 }
}

static AVFrame *get_video_frame(OutputStream *ost)
{
 AVCodecContext *c = ost->enc;

 /* check if we want to generate more frames */
 if (av_compare_ts(ost->next_pts, c->time_base,
 STREAM_DURATION, (AVRational){ 1, 1 }) > 0)
 return NULL;

 /* when we pass a frame to the encoder, it may keep a reference to it
 * internally; make sure we do not overwrite it here */
 if (av_frame_make_writable(ost->frame) < 0)
 exit(1);

 if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
 /* as we only generate a YUV420P picture, we must convert it
 * to the codec pixel format if needed */
 if (!ost->sws_ctx) {
 ost->sws_ctx = sws_getContext(c->width, c->height,
 AV_PIX_FMT_YUV420P,
 c->width, c->height,
 c->pix_fmt,
 SCALE_FLAGS, NULL, NULL, NULL);
 if (!ost->sws_ctx) {
 fprintf(stderr,
 "Could not initialize the conversion context\n");
 exit(1);
 }
 }
 fill_yuv_image(ost->tmp_frame, ost->next_pts, c->width, c->height);
 sws_scale(ost->sws_ctx, (const uint8_t * const *) ost->tmp_frame->data,
 ost->tmp_frame->linesize, 0, c->height, ost->frame->data,
 ost->frame->linesize);
 } else {
 fill_yuv_image(ost->frame, ost->next_pts, c->width, c->height);
 }

 ost->frame->pts = ost->next_pts++;

 return ost->frame;
}

/*
 * encode one video frame and send it to the muxer
 * return 1 when encoding is finished, 0 otherwise
 */
static int write_video_frame(AVFormatContext *oc, OutputStream *ost)
{
 return write_frame(oc, ost->enc, ost->st, get_video_frame(ost), ost->tmp_pkt);
}

static void close_stream(AVFormatContext *oc, OutputStream *ost)
{
 avcodec_free_context(&ost->enc);
 av_frame_free(&ost->frame);
 av_frame_free(&ost->tmp_frame);
 av_packet_free(&ost->tmp_pkt);
 sws_freeContext(ost->sws_ctx);
 swr_free(&ost->swr_ctx);
}

/**************************************************************/
/* media file output */

int main(int argc, char **argv)
{
 OutputStream video_st = { 0 }, audio_st = { 0 };
 const AVOutputFormat *fmt;
 const char *filename;
 AVFormatContext *oc;
 const AVCodec *audio_codec, *video_codec;
 int ret;
 int have_video = 0, have_audio = 0;
 int encode_video = 0, encode_audio = 0;
 AVDictionary *opt = NULL;
 int i;

 if (argc < 2) {
 printf("usage: %s output_file\n"
 "API example program to output a media file with libavformat.\n"
 "This program generates a synthetic audio and video stream, encodes and\n"
 "muxes them into a file named output_file.\n"
 "The output format is automatically guessed according to the file extension.\n"
 "Raw images can also be output by using '%%d' in the filename.\n"
 "\n", argv[0]);
 return 1;
 }

 filename = argv[1];

 av_dict_set(&opt, "movflags", "frag_keyframe+separate_moof+omit_tfhd_offset+empty_moov", 0);

 /* allocate the output media context */
 avformat_alloc_output_context2(&oc, NULL, NULL, filename);
 if (!oc) {
 printf("Could not deduce output format from file extension: using MPEG.\n");
 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
 }
 if (!oc)
 return 1;

 fmt = oc->oformat;

 /* Add the audio and video streams using the default format codecs
 * and initialize the codecs. */
 if (fmt->video_codec != AV_CODEC_ID_NONE) {
 add_stream(&video_st, oc, &video_codec, fmt->video_codec);
 have_video = 1;
 encode_video = 1;
 }

 /* Now that all the parameters are set, we can open the audio and
 * video codecs and allocate the necessary encode buffers. */
 if (have_video)
 open_video(oc, video_codec, &video_st, opt);


 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'\n", filename);
 return 1;
 }
 }

 /* Write the stream header, if any. */
 ret = avformat_write_header(oc, &opt);
 if (ret < 0) {
 fprintf(stderr, "Error occurred when opening output file\n");
 return 1;
 }

 while (encode_video || encode_audio) {
 /* select the stream to encode */
 if (encode_video &&
 (!encode_audio || av_compare_ts(video_st.next_pts, video_st.enc->time_base,
 audio_st.next_pts, audio_st.enc->time_base) <= 0)) {
 encode_video = !write_video_frame(oc, &video_st);
 }
 }

 av_write_trailer(oc);

 /* Close each codec. */
 if (have_video)
 close_stream(oc, &video_st);
 if (have_audio)
 close_stream(oc, &audio_st);

 if (!(fmt->flags & AVFMT_NOFILE))
 /* Close the output file. */
 avio_closep(&oc->pb);

 /* free the stream */
 avformat_free_context(oc);

 return 0;
}
</cmath></cstring></cstdio></cstdlib>

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