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Richard Stallman et le logiciel libre
19 octobre 2011, par
Mis à jour : Mai 2013
Langue : français
Type : Texte
Autres articles (96)
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Emballe médias : à quoi cela sert ?
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Il crée des "médias", à savoir : un "média" est un article au sens SPIP créé automatiquement lors du téléversement d’un document qu’il soit audio, vidéo, image ou textuel ; un seul document ne peut être lié à un article dit "média" ;
Sur d’autres sites (7998)
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About the delay of Electron playing FFpmeg transcoded video
26 juillet 2020, par YohannIn the Electron project, you need to try to play the video screen of the camera


The camera is Haikang’s webcam


Get real-time video stream through RTSP protocol


rtsp://admin:admin@192.168.0.253/main/Channels/

There will be a delay of about 3s when playing through the VLC player


Then when used in the project, create a websocket service in Electron through the main process, decode the rtsp video through fluent-ffmpeg, and convert it to flv stream and push it to the rendering process


import * as express from 'express'
import * as expressWebSocket from 'express-ws'
import ffmpeg from 'fluent-ffmpeg'
import webSocketStream from 'websocket-stream/stream'
const path = require('path')

let ffmpegPath
if (process.env.NODE_ENV === 'development') {
 ffmpegPath = path.join(__static, 'ffmpeg', 'bin', 'ffmpeg.exe')
} else {
 ffmpegPath = path.join(process.cwd(), 'ffmpeg', 'bin', 'ffmpeg.exe')
}
ffmpeg.setFfmpegPath(ffmpegPath)

// Start video transcoding service
function videoServer () {
 let app = express()
 app.use(express.static(__dirname))
 expressWebSocket(app, null, {
 perMessageDeflate: true
 })
 app.ws('/rtsp/', rtspRequestHandle)
 app.listen(8888)
 console.log('Create a monitoring service')
}

//RTSP transcoding method
function rtspRequestHandle (ws, req) {
 console.log('rtsp request handle')
 const stream = webSocketStream(ws, {
 binary: true,
 browserBufferTimeout: 1000000
 },
 {
 browserBufferTimeout: 1000000
 })
 let url = req.query.url
 console.log('rtsp url:', url)
 try {
 ffmpeg(url)
 .addInputOption('-rtsp_transport', 'tcp', '-buffer_size', '102400') // Here you can add some RTSP optimized parameters
 .outputOptions([
 '-fflags',
 'nobuffer',
 '-tune',
 'zerolatency'
 ])
 .on('start', function () {
 console.log(url, 'Stream started.')
 })
 .on('codecData', function () {
 console.log(url, 'Stream codecData.')
 })
 .on('error', function (err) {
 console.log(url, 'An error occured: ', err.message)
 })
 .on('end', function () {
 console.log(url, 'Stream end!')
 })
 .outputFormat('flv').videoCodec('copy').noAudio().pipe(stream)
 } catch (error) {
 console.log(error)
 }
}

export default videoServer


The rendering process parses the video stream and plays the video through flv.js


<template>
 <div class="video">
 <video class="video-box" ref="player"></video>
 </div>
</template>

<code class="echappe-js"><script>&#xA; import flvjs from &#x27;flv.js&#x27;&#xA; export default {&#xA; name: &#x27;videopage&#x27;,&#xA; props: {&#xA; rtsp: String&#xA; },&#xA; data () {&#xA; return {&#xA; player: null&#xA; }&#xA; },&#xA; mounted () {&#xA; console.log(flvjs.isSupported())&#xA; if (flvjs.isSupported()) {&#xA; let video = this.$refs.player&#xA; console.log(video)&#xA; if (video) {&#xA; this.player = flvjs.createPlayer({&#xA; type: &#x27;flv&#x27;,&#xA; isLive: true,&#xA; url: &#x27;ws://localhost:8888/rtsp/?url=&#x27; &#x2B; this.rtsp&#xA; }, {&#xA; enableStashBuffer: true&#xA; })&#xA; console.log(this.player)&#xA; this.player.attachMediaElement(video)&#xA; try {&#xA; this.player.load()&#xA; this.player.play()&#xA; } catch (error) {&#xA; console.log(error)&#xA; }&#xA; }&#xA; }&#xA; },&#xA; methods: {&#xA; getCurrentFrame () {&#xA; let video = this.$refs.player&#xA; let scale = 1&#xA; let canvas = document.createElement(&#x27;canvas&#x27;)&#xA; canvas.width = video.videoWidth * scale&#xA; canvas.height = video.videoHeight * scale&#xA; canvas.getContext(&#x27;2d&#x27;).drawImage(video, 0, 0, canvas.width, canvas.height)&#xA; return canvas.toDataURL(&#x27;image/png&#x27;)&#xA; }&#xA; },&#xA; beforeDestroy () {&#xA; this.player &amp;&amp; this.player.destory &amp;&amp; this.player.destory()&#xA; }&#xA; }&#xA;</script>




Then there will be a delay of about 3s when playing, and the delay will increase with the playing time


There will be a delay of 10 minutes in the later period


Is there any way to control this delay time


Or is there any other decoding scheme that can be used ?


Solutions that can support electron


-
"Pixel format 'yuvj420p' is not supported" when converting image to video using CUDA hardware acceleration
11 février 2020, par laurentI’m trying to convert an image to a video using CUDA hardware acceleration but I can’t get it to work.
The basic command I have is this one :
ffmpeg -y -hwaccel cuvid -i tests/MediaSamples/portrait_0.jpg -t 10 out.mp4
And I’m getting this error :
[AVHWFramesContext @ 0x32d3f00] Pixel format 'yuvj420p' is not supported
[mjpeg @ 0x2d18480] Error initializing a CUDA frame pool
cuvid hwaccel requested for input stream #0:0, but cannot be initialized.
Error while decoding stream #0:0: Invalid argumentI’ve tried setting the pixel format like so, but that didn’t help :
ffmpeg -y -hwaccel cuvid -pix_fmt yuv420p -i tests/MediaSamples/portrait_0.jpg -t 10 out.mp4
I’ve also tried many other flags but can’t get anything to work. Any idea what the issue might be ?
For information this is the full log :
ffmpeg version N-96615-gc35382a Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.12) 20160609
configuration: --enable-nonfree --disable-shared --enable-gpl --enable-openssl --enable-libx264 --enable-cuda-sdk --enable-nvenc --enable-cuda --enable-cuvid --enable-libnpp --extra-cflags='-I/usr/local/ssl/include -I/usr/local/cuda/include -I/usr/local/include -L/usr/local/ssl/lib -Wl,-rpath=/usr/local/ssl/lib' --extra-ldflags=-L/usr/local/cuda/lib64
libavutil 56. 38.100 / 56. 38.100
libavcodec 58. 67.101 / 58. 67.101
libavformat 58. 37.100 / 58. 37.100
libavdevice 58. 9.103 / 58. 9.103
libavfilter 7. 73.100 / 7. 73.100
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
Input #0, image2, from 'tests/MediaSamples/portrait_0.jpg':
Duration: 00:00:00.04, start: 0.000000, bitrate: 40237 kb/s
Stream #0:0: Video: mjpeg (Progressive), yuvj420p(pc, bt470bg/unknown/unknown), 1600x900 [SAR 72:72 DAR 16:9], 25 tbr, 25 tbn, 25 tbc
Stream mapping:
Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[AVHWFramesContext @ 0x32d3f00] Pixel format 'yuvj420p' is not supported
[mjpeg @ 0x2d18480] Error initializing a CUDA frame pool
cuvid hwaccel requested for input stream #0:0, but cannot be initialized.
Error while decoding stream #0:0: Invalid argument
[libx264 @ 0x2d1e840] using SAR=1/1
[libx264 @ 0x2d1e840] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
[libx264 @ 0x2d1e840] profile High, level 4.0
[libx264 @ 0x2d1e840] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - 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=24 lookahead_threads=4 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=25 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
Output #0, mp4, to 'out.mp4':
Metadata:
encoder : Lavf58.37.100
Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuvj420p(pc), 1600x900 [SAR 72:72 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc
Metadata:
encoder : Lavc58.67.101 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame= 0 fps=0.0 q=0.0 Lsize= 0kB time=00:00:00.00 bitrate=N/A speed= 0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Conversion failed! -
Why does adding audio stream to ffmpeg's libavcodec output container cause a crash ?
29 mars 2021, par SniggerfardimungusAs it stands, my project correctly uses libavcodec to decode a video, where each frame is manipulated (it doesn't matter how) and output to a new video. I've cobbled this together from examples found online, and it works. The result is a perfect .mp4 of the manipulated frames, minus the audio.


My problem is, when I try to add an audio stream to the output container, I get a crash in mux.c that I can't explain. It's in
static int compute_muxer_pkt_fields(AVFormatContext *s, AVStream *st, AVPacket *pkt). Wherest->internal->priv_pts->val = pkt->dts;is attempted,priv_ptsis nullptr.

I don't recall the version number, but this is from a November 4, 2020 ffmpeg build from git.


My
MediaContentMgris much bigger than what I have here. I'm stripping out everything to do with the frame manipulation, so if I'm missing anything, please let me know and I'll edit.

The code that, when added, triggers the nullptr exception, is called out inline


The .h :


#ifndef _API_EXAMPLE_H
#define _API_EXAMPLE_H

#include <glad></glad>glad.h>
#include <glfw></glfw>glfw3.h>
#include "glm/glm.hpp"

extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavutil></libavutil>avutil.h>
#include <libavutil></libavutil>opt.h>
#include <libswscale></libswscale>swscale.h>
}

#include "shader_s.h"

class MediaContainerMgr {
public:
 MediaContainerMgr(const std::string& infile, const std::string& vert, const std::string& frag, 
 const glm::vec3* extents);
 ~MediaContainerMgr();
 void render();
 bool recording() { return m_recording; }

 // Major thanks to "shi-yan" who helped make this possible:
 // https://github.com/shi-yan/videosamples/blob/master/libavmp4encoding/main.cpp
 bool init_video_output(const std::string& video_file_name, unsigned int width, unsigned int height);
 bool output_video_frame(uint8_t* buf);
 bool finalize_output();

private:
 AVFormatContext* m_format_context;
 AVCodec* m_video_codec;
 AVCodec* m_audio_codec;
 AVCodecParameters* m_video_codec_parameters;
 AVCodecParameters* m_audio_codec_parameters;
 AVCodecContext* m_codec_context;
 AVFrame* m_frame;
 AVPacket* m_packet;
 uint32_t m_video_stream_index;
 uint32_t m_audio_stream_index;
 
 void init_rendering(const glm::vec3* extents);
 int decode_packet();

 // For writing the output video:
 void free_output_assets();
 bool m_recording;
 AVOutputFormat* m_output_format;
 AVFormatContext* m_output_format_context;
 AVCodec* m_output_video_codec;
 AVCodecContext* m_output_video_codec_context;
 AVFrame* m_output_video_frame;
 SwsContext* m_output_scale_context;
 AVStream* m_output_video_stream;
 
 AVCodec* m_output_audio_codec;
 AVStream* m_output_audio_stream;
 AVCodecContext* m_output_audio_codec_context;
};

#endif


And, the hellish .cpp :


#include 
#include 
#include 
#include 
#include 

#include "media_container_manager.h"

MediaContainerMgr::MediaContainerMgr(const std::string& infile, const std::string& vert, const std::string& frag,
 const glm::vec3* extents) :
 m_video_stream_index(-1),
 m_audio_stream_index(-1),
 m_recording(false),
 m_output_format(nullptr),
 m_output_format_context(nullptr),
 m_output_video_codec(nullptr),
 m_output_video_codec_context(nullptr),
 m_output_video_frame(nullptr),
 m_output_scale_context(nullptr),
 m_output_video_stream(nullptr)
{
 // AVFormatContext holds header info from the format specified in the container:
 m_format_context = avformat_alloc_context();
 if (!m_format_context) {
 throw "ERROR could not allocate memory for Format Context";
 }
 
 // open the file and read its header. Codecs are not opened here.
 if (avformat_open_input(&m_format_context, infile.c_str(), NULL, NULL) != 0) {
 throw "ERROR could not open input file for reading";
 }

 printf("format %s, duration %lldus, bit_rate %lld\n", m_format_context->iformat->name, m_format_context->duration, m_format_context->bit_rate);
 //read avPackets (?) from the avFormat (?) to get stream info. This populates format_context->streams.
 if (avformat_find_stream_info(m_format_context, NULL) < 0) {
 throw "ERROR could not get stream info";
 }

 for (unsigned int i = 0; i < m_format_context->nb_streams; i++) {
 AVCodecParameters* local_codec_parameters = NULL;
 local_codec_parameters = m_format_context->streams[i]->codecpar;
 printf("AVStream->time base before open coded %d/%d\n", m_format_context->streams[i]->time_base.num, m_format_context->streams[i]->time_base.den);
 printf("AVStream->r_frame_rate before open coded %d/%d\n", m_format_context->streams[i]->r_frame_rate.num, m_format_context->streams[i]->r_frame_rate.den);
 printf("AVStream->start_time %" PRId64 "\n", m_format_context->streams[i]->start_time);
 printf("AVStream->duration %" PRId64 "\n", m_format_context->streams[i]->duration);
 printf("duration(s): %lf\n", (float)m_format_context->streams[i]->duration / m_format_context->streams[i]->time_base.den * m_format_context->streams[i]->time_base.num);
 AVCodec* local_codec = NULL;
 local_codec = avcodec_find_decoder(local_codec_parameters->codec_id);
 if (local_codec == NULL) {
 throw "ERROR unsupported codec!";
 }

 if (local_codec_parameters->codec_type == AVMEDIA_TYPE_VIDEO) {
 if (m_video_stream_index == -1) {
 m_video_stream_index = i;
 m_video_codec = local_codec;
 m_video_codec_parameters = local_codec_parameters;
 }
 m_height = local_codec_parameters->height;
 m_width = local_codec_parameters->width;
 printf("Video Codec: resolution %dx%d\n", m_width, m_height);
 }
 else if (local_codec_parameters->codec_type == AVMEDIA_TYPE_AUDIO) {
 if (m_audio_stream_index == -1) {
 m_audio_stream_index = i;
 m_audio_codec = local_codec;
 m_audio_codec_parameters = local_codec_parameters;
 }
 printf("Audio Codec: %d channels, sample rate %d\n", local_codec_parameters->channels, local_codec_parameters->sample_rate);
 }

 printf("\tCodec %s ID %d bit_rate %lld\n", local_codec->name, local_codec->id, local_codec_parameters->bit_rate);
 }

 m_codec_context = avcodec_alloc_context3(m_video_codec);
 if (!m_codec_context) {
 throw "ERROR failed to allocate memory for AVCodecContext";
 }

 if (avcodec_parameters_to_context(m_codec_context, m_video_codec_parameters) < 0) {
 throw "ERROR failed to copy codec params to codec context";
 }

 if (avcodec_open2(m_codec_context, m_video_codec, NULL) < 0) {
 throw "ERROR avcodec_open2 failed to open codec";
 }

 m_frame = av_frame_alloc();
 if (!m_frame) {
 throw "ERROR failed to allocate AVFrame memory";
 }

 m_packet = av_packet_alloc();
 if (!m_packet) {
 throw "ERROR failed to allocate AVPacket memory";
 }
}

MediaContainerMgr::~MediaContainerMgr() {
 avformat_close_input(&m_format_context);
 av_packet_free(&m_packet);
 av_frame_free(&m_frame);
 avcodec_free_context(&m_codec_context);


 glDeleteVertexArrays(1, &m_VAO);
 glDeleteBuffers(1, &m_VBO);
}


bool MediaContainerMgr::advance_frame() {
 while (true) {
 if (av_read_frame(m_format_context, m_packet) < 0) {
 // Do we actually need to unref the packet if it failed?
 av_packet_unref(m_packet);
 continue;
 //return false;
 }
 else {
 if (m_packet->stream_index == m_video_stream_index) {
 //printf("AVPacket->pts %" PRId64 "\n", m_packet->pts);
 int response = decode_packet();
 av_packet_unref(m_packet);
 if (response != 0) {
 continue;
 //return false;
 }
 return true;
 }
 else {
 printf("m_packet->stream_index: %d\n", m_packet->stream_index);
 printf(" m_packet->pts: %lld\n", m_packet->pts);
 printf(" mpacket->size: %d\n", m_packet->size);
 if (m_recording) {
 int err = 0;
 //err = avcodec_send_packet(m_output_video_codec_context, m_packet);
 printf(" encoding error: %d\n", err);
 }
 }
 }

 // We're done with the packet (it's been unpacked to a frame), so deallocate & reset to defaults:
/*
 if (m_frame == NULL)
 return false;

 if (m_frame->data[0] == NULL || m_frame->data[1] == NULL || m_frame->data[2] == NULL) {
 printf("WARNING: null frame data");
 continue;
 }
*/
 }
}

int MediaContainerMgr::decode_packet() {
 // Supply raw packet data as input to a decoder
 // https://ffmpeg.org/doxygen/trunk/group__lavc__decoding.html#ga58bc4bf1e0ac59e27362597e467efff3
 int response = avcodec_send_packet(m_codec_context, m_packet);

 if (response < 0) {
 char buf[256];
 av_strerror(response, buf, 256);
 printf("Error while receiving a frame from the decoder: %s\n", buf);
 return response;
 }

 // Return decoded output data (into a frame) from a decoder
 // https://ffmpeg.org/doxygen/trunk/group__lavc__decoding.html#ga11e6542c4e66d3028668788a1a74217c
 response = avcodec_receive_frame(m_codec_context, m_frame);
 if (response == AVERROR(EAGAIN) || response == AVERROR_EOF) {
 return response;
 } else if (response < 0) {
 char buf[256];
 av_strerror(response, buf, 256);
 printf("Error while receiving a frame from the decoder: %s\n", buf);
 return response;
 } else {
 printf(
 "Frame %d (type=%c, size=%d bytes) pts %lld key_frame %d [DTS %d]\n",
 m_codec_context->frame_number,
 av_get_picture_type_char(m_frame->pict_type),
 m_frame->pkt_size,
 m_frame->pts,
 m_frame->key_frame,
 m_frame->coded_picture_number
 );
 }
 return 0;
}


bool MediaContainerMgr::init_video_output(const std::string& video_file_name, unsigned int width, unsigned int height) {
 if (m_recording)
 return true;
 m_recording = true;

 advance_to(0L); // I've deleted the implmentation. Just seeks to beginning of vid. Works fine.

 if (!(m_output_format = av_guess_format(nullptr, video_file_name.c_str(), nullptr))) {
 printf("Cannot guess output format.\n");
 return false;
 }

 int err = avformat_alloc_output_context2(&m_output_format_context, m_output_format, nullptr, video_file_name.c_str());
 if (err < 0) {
 printf("Failed to allocate output context.\n");
 return false;
 }

 //TODO(P0): Break out the video and audio inits into their own methods.
 m_output_video_codec = avcodec_find_encoder(m_output_format->video_codec);
 if (!m_output_video_codec) {
 printf("Failed to create video codec.\n");
 return false;
 }
 m_output_video_stream = avformat_new_stream(m_output_format_context, m_output_video_codec);
 if (!m_output_video_stream) {
 printf("Failed to find video format.\n");
 return false;
 } 
 m_output_video_codec_context = avcodec_alloc_context3(m_output_video_codec);
 if (!m_output_video_codec_context) {
 printf("Failed to create video codec context.\n");
 return(false);
 }
 m_output_video_stream->codecpar->codec_id = m_output_format->video_codec;
 m_output_video_stream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
 m_output_video_stream->codecpar->width = width;
 m_output_video_stream->codecpar->height = height;
 m_output_video_stream->codecpar->format = AV_PIX_FMT_YUV420P;
 // Use the same bit rate as the input stream.
 m_output_video_stream->codecpar->bit_rate = m_format_context->streams[m_video_stream_index]->codecpar->bit_rate;
 m_output_video_stream->avg_frame_rate = m_format_context->streams[m_video_stream_index]->avg_frame_rate;
 avcodec_parameters_to_context(m_output_video_codec_context, m_output_video_stream->codecpar);
 m_output_video_codec_context->time_base = m_format_context->streams[m_video_stream_index]->time_base;
 
 //TODO(P1): Set these to match the input stream?
 m_output_video_codec_context->max_b_frames = 2;
 m_output_video_codec_context->gop_size = 12;
 m_output_video_codec_context->framerate = m_format_context->streams[m_video_stream_index]->r_frame_rate;
 //m_output_codec_context->refcounted_frames = 0;
 if (m_output_video_stream->codecpar->codec_id == AV_CODEC_ID_H264) {
 av_opt_set(m_output_video_codec_context, "preset", "ultrafast", 0);
 } else if (m_output_video_stream->codecpar->codec_id == AV_CODEC_ID_H265) {
 av_opt_set(m_output_video_codec_context, "preset", "ultrafast", 0);
 } else {
 av_opt_set_int(m_output_video_codec_context, "lossless", 1, 0);
 }
 avcodec_parameters_from_context(m_output_video_stream->codecpar, m_output_video_codec_context);

 m_output_audio_codec = avcodec_find_encoder(m_output_format->audio_codec);
 if (!m_output_audio_codec) {
 printf("Failed to create audio codec.\n");
 return false;
 }


I've commented out all of the audio stream init beyond this next line, because this is where
the trouble begins. Creating this output stream causes the null reference I mentioned. If I
uncomment everything below here, I still get the null deref. If I comment out this line, the
deref exception vanishes. (IOW, I commented out more and more code until I found that this
was the trigger that caused the problem.)


I assume that there's something I'm doing wrong in the rest of the commented out code, that,
when fixed, will fix the nullptr and give me a working audio stream.


m_output_audio_stream = avformat_new_stream(m_output_format_context, m_output_audio_codec);
 if (!m_output_audio_stream) {
 printf("Failed to find audio format.\n");
 return false;
 }
 /*
 m_output_audio_codec_context = avcodec_alloc_context3(m_output_audio_codec);
 if (!m_output_audio_codec_context) {
 printf("Failed to create audio codec context.\n");
 return(false);
 }
 m_output_audio_stream->codecpar->codec_id = m_output_format->audio_codec;
 m_output_audio_stream->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
 m_output_audio_stream->codecpar->format = m_format_context->streams[m_audio_stream_index]->codecpar->format;
 m_output_audio_stream->codecpar->bit_rate = m_format_context->streams[m_audio_stream_index]->codecpar->bit_rate;
 m_output_audio_stream->avg_frame_rate = m_format_context->streams[m_audio_stream_index]->avg_frame_rate;
 avcodec_parameters_to_context(m_output_audio_codec_context, m_output_audio_stream->codecpar);
 m_output_audio_codec_context->time_base = m_format_context->streams[m_audio_stream_index]->time_base;
 */

 //TODO(P2): Free assets that have been allocated.
 err = avcodec_open2(m_output_video_codec_context, m_output_video_codec, nullptr);
 if (err < 0) {
 printf("Failed to open codec.\n");
 return false;
 }

 if (!(m_output_format->flags & AVFMT_NOFILE)) {
 err = avio_open(&m_output_format_context->pb, video_file_name.c_str(), AVIO_FLAG_WRITE);
 if (err < 0) {
 printf("Failed to open output file.");
 return false;
 }
 }

 err = avformat_write_header(m_output_format_context, NULL);
 if (err < 0) {
 printf("Failed to write header.\n");
 return false;
 }

 av_dump_format(m_output_format_context, 0, video_file_name.c_str(), 1);

 return true;
}


//TODO(P2): make this a member. (Thanks to https://emvlo.wordpress.com/2016/03/10/sws_scale/)
void PrepareFlipFrameJ420(AVFrame* pFrame) {
 for (int i = 0; i < 4; i++) {
 if (i)
 pFrame->data[i] += pFrame->linesize[i] * ((pFrame->height >> 1) - 1);
 else
 pFrame->data[i] += pFrame->linesize[i] * (pFrame->height - 1);
 pFrame->linesize[i] = -pFrame->linesize[i];
 }
}


This is where we take an altered frame and write it to the output container. This works fine
as long as we haven't set up an audio stream in the output container.


bool MediaContainerMgr::output_video_frame(uint8_t* buf) {
 int err;

 if (!m_output_video_frame) {
 m_output_video_frame = av_frame_alloc();
 m_output_video_frame->format = AV_PIX_FMT_YUV420P;
 m_output_video_frame->width = m_output_video_codec_context->width;
 m_output_video_frame->height = m_output_video_codec_context->height;
 err = av_frame_get_buffer(m_output_video_frame, 32);
 if (err < 0) {
 printf("Failed to allocate output frame.\n");
 return false;
 }
 }

 if (!m_output_scale_context) {
 m_output_scale_context = sws_getContext(m_output_video_codec_context->width, m_output_video_codec_context->height, 
 AV_PIX_FMT_RGB24,
 m_output_video_codec_context->width, m_output_video_codec_context->height, 
 AV_PIX_FMT_YUV420P, SWS_BICUBIC, nullptr, nullptr, nullptr);
 }

 int inLinesize[1] = { 3 * m_output_video_codec_context->width };
 sws_scale(m_output_scale_context, (const uint8_t* const*)&buf, inLinesize, 0, m_output_video_codec_context->height,
 m_output_video_frame->data, m_output_video_frame->linesize);
 PrepareFlipFrameJ420(m_output_video_frame);
 //TODO(P0): Switch m_frame to be m_input_video_frame so I don't end up using the presentation timestamp from
 // an audio frame if I threadify the frame reading.
 m_output_video_frame->pts = m_frame->pts;
 printf("Output PTS: %d, time_base: %d/%d\n", m_output_video_frame->pts,
 m_output_video_codec_context->time_base.num, m_output_video_codec_context->time_base.den);
 err = avcodec_send_frame(m_output_video_codec_context, m_output_video_frame);
 if (err < 0) {
 printf(" ERROR sending new video frame output: ");
 switch (err) {
 case AVERROR(EAGAIN):
 printf("AVERROR(EAGAIN): %d\n", err);
 break;
 case AVERROR_EOF:
 printf("AVERROR_EOF: %d\n", err);
 break;
 case AVERROR(EINVAL):
 printf("AVERROR(EINVAL): %d\n", err);
 break;
 case AVERROR(ENOMEM):
 printf("AVERROR(ENOMEM): %d\n", err);
 break;
 }

 return false;
 }

 AVPacket pkt;
 av_init_packet(&pkt);
 pkt.data = nullptr;
 pkt.size = 0;
 pkt.flags |= AV_PKT_FLAG_KEY;
 int ret = 0;
 if ((ret = avcodec_receive_packet(m_output_video_codec_context, &pkt)) == 0) {
 static int counter = 0;
 printf("pkt.key: 0x%08x, pkt.size: %d, counter:\n", pkt.flags & AV_PKT_FLAG_KEY, pkt.size, counter++);
 uint8_t* size = ((uint8_t*)pkt.data);
 printf("sizes: %d %d %d %d %d %d %d %d %d\n", size[0], size[1], size[2], size[2], size[3], size[4], size[5], size[6], size[7]);
 av_interleaved_write_frame(m_output_format_context, &pkt);
 }
 printf("push: %d\n", ret);
 av_packet_unref(&pkt);

 return true;
}

bool MediaContainerMgr::finalize_output() {
 if (!m_recording)
 return true;

 AVPacket pkt;
 av_init_packet(&pkt);
 pkt.data = nullptr;
 pkt.size = 0;

 for (;;) {
 avcodec_send_frame(m_output_video_codec_context, nullptr);
 if (avcodec_receive_packet(m_output_video_codec_context, &pkt) == 0) {
 av_interleaved_write_frame(m_output_format_context, &pkt);
 printf("final push:\n");
 } else {
 break;
 }
 }

 av_packet_unref(&pkt);

 av_write_trailer(m_output_format_context);
 if (!(m_output_format->flags & AVFMT_NOFILE)) {
 int err = avio_close(m_output_format_context->pb);
 if (err < 0) {
 printf("Failed to close file. err: %d\n", err);
 return false;
 }
 }

 return true;
}


EDIT
The call stack on the crash (which I should have included in the original question) :


avformat-58.dll!compute_muxer_pkt_fields(AVFormatContext * s, AVStream * st, AVPacket * pkt) Line 630 C
avformat-58.dll!write_packet_common(AVFormatContext * s, AVStream * st, AVPacket * pkt, int interleaved) Line 1122 C
avformat-58.dll!write_packets_common(AVFormatContext * s, AVPacket * pkt, int interleaved) Line 1186 C
avformat-58.dll!av_interleaved_write_frame(AVFormatContext * s, AVPacket * pkt) Line 1241 C
CamBot.exe!MediaContainerMgr::output_video_frame(unsigned char * buf) Line 553 C++
CamBot.exe!main() Line 240 C++


If I move the call to avformat_write_header so it's immediately before the audio stream initialization, I still get a crash, but in a different place. The crash happens on line 6459 of movenc.c, where we have :


/* Non-seekable output is ok if using fragmentation. If ism_lookahead
 * is enabled, we don't support non-seekable output at all. */
if (!(s->pb->seekable & AVIO_SEEKABLE_NORMAL) && // CRASH IS HERE
 (!(mov->flags & FF_MOV_FLAG_FRAGMENT) || mov->ism_lookahead)) {
 av_log(s, AV_LOG_ERROR, "muxer does not support non seekable output\n");
 return AVERROR(EINVAL);
}


The exception is a nullptr exception, where s->pb is NULL. The call stack is :


avformat-58.dll!mov_init(AVFormatContext * s) Line 6459 C
avformat-58.dll!init_muxer(AVFormatContext * s, AVDictionary * * options) Line 407 C
[Inline Frame] avformat-58.dll!avformat_init_output(AVFormatContext *) Line 489 C
avformat-58.dll!avformat_write_header(AVFormatContext * s, AVDictionary * * options) Line 512 C
CamBot.exe!MediaContainerMgr::init_video_output(const std::string & video_file_name, unsigned int width, unsigned int height) Line 424 C++
CamBot.exe!main() Line 183 C++


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