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Carte de Schillerkiez
13 mai 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Texte
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Sur d’autres sites (6275)
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ffmpeg GRAY16 stream over network
28 novembre 2023, par Norbert P.Im working in a school project where we need to use depth cameras. The camera produces color and depth (in other words 16bit grayscale image). We decided to use ffmpeg, as later on compression could be very useful. For now we got some basic stream running form one PC to other. These settings include :


- 

- rtmp
- flv as container
- pixel format AV_PIX_FMT_YUV420P
- codec AV_CODEC_ID_H264










The problem we are having is with grayscale image. Not every codec is able to cope with this format, so as not every protocol able to work with given codec. I got some settings "working" but receiver side is just stuck on avformat_open_input() method.
I have also tested it with commandline where ffmpeg is listening for connection and same happens.


I include a minimum "working" example of client code. Server can be tested with "ffmpeg.exe -f apng -listen 1 -i rtmp ://localhost:9999/stream/stream1 -c copy -f apng -listen 1 rtmp ://localhost:2222/live/l" or code below. I get no warnings, ffmpeg is newest version installed with "vcpkg install —triplet x64-windows ffmpeg[ffmpeg,ffprobe,zlib]" on windows or packet manager on linux.


The question : Did I miss something ? How do I get it to work ? If you have any better ideas I would very gladly consider them. In the end I need 16 bits of lossless transmission, could be split between channels etc. which I also tried with same effect.


Client code that would have camera and connect to server :


extern "C" {
#include <libavutil></libavutil>opt.h>
#include <libavcodec></libavcodec>avcodec.h>
#include <libavutil></libavutil>channel_layout.h>
#include <libavutil></libavutil>common.h>
#include <libavformat></libavformat>avformat.h>
#include <libavcodec></libavcodec>avcodec.h>
#include <libavutil></libavutil>imgutils.h>
}

int main() {

 std::string container = "apng";
 AVCodecID codec_id = AV_CODEC_ID_APNG;
 AVPixelFormat pixFormat = AV_PIX_FMT_GRAY16BE;

 AVFormatContext* format_ctx;
 AVCodec* out_codec;
 AVStream* out_stream;
 AVCodecContext* out_codec_ctx;
 AVFrame* frame;
 uint8_t* data;

 std::string server = "rtmp://localhost:9999/stream/stream1";

 int width = 1280, height = 720, fps = 30, bitrate = 1000000;

 //initialize format context for output with flv and no filename
 avformat_alloc_output_context2(&format_ctx, nullptr, container.c_str(), server.c_str());
 if (!format_ctx) {
 return 1;
 }

 //AVIOContext for accessing the resource indicated by url
 if (!(format_ctx->oformat->flags & AVFMT_NOFILE)) {
 int avopen_ret = avio_open(&format_ctx->pb, server.c_str(),
 AVIO_FLAG_WRITE);// , nullptr, nullptr);
 if (avopen_ret < 0) {
 fprintf(stderr, "failed to open stream output context, stream will not work\n");
 return 1;
 }
 }


 const AVCodec* tmp_out_codec = avcodec_find_encoder(codec_id);
 //const AVCodec* tmp_out_codec = avcodec_find_encoder_by_name("hevc");
 out_codec = const_cast(tmp_out_codec);
 if (!(out_codec)) {
 fprintf(stderr, "Could not find encoder for '%s'\n",
 avcodec_get_name(codec_id));

 return 1;
 }

 out_stream = avformat_new_stream(format_ctx, out_codec);
 if (!out_stream) {
 fprintf(stderr, "Could not allocate stream\n");
 return 1;
 }

 out_codec_ctx = avcodec_alloc_context3(out_codec);

 const AVRational timebase = { 60000, fps };
 const AVRational dst_fps = { fps, 1 };
 av_log_set_level(AV_LOG_VERBOSE);
 //codec_ctx->codec_tag = 0;
 //codec_ctx->codec_id = codec_id;
 out_codec_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
 out_codec_ctx->width = width;
 out_codec_ctx->height = height;
 out_codec_ctx->gop_size = 1;
 out_codec_ctx->time_base = timebase;
 out_codec_ctx->pix_fmt = pixFormat;
 out_codec_ctx->framerate = dst_fps;
 out_codec_ctx->time_base = av_inv_q(dst_fps);
 out_codec_ctx->bit_rate = bitrate;
 //if (fctx->oformat->flags & AVFMT_GLOBALHEADER)
 //{
 // codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
 //}

 out_stream->time_base = out_codec_ctx->time_base; //will be set afterwards by avformat_write_header to 1/1000

 int ret = avcodec_parameters_from_context(out_stream->codecpar, out_codec_ctx);
 if (ret < 0)
 {
 fprintf(stderr, "Could not initialize stream codec parameters!\n");
 return 1;
 }

 AVDictionary* codec_options = nullptr;
 av_dict_set(&codec_options, "tune", "zerolatency", 0);

 // open video encoder
 ret = avcodec_open2(out_codec_ctx, out_codec, &codec_options);
 if (ret < 0)
 {
 fprintf(stderr, "Could not open video encoder!\n");
 return 1;
 }
 av_dict_free(&codec_options);

 out_stream->codecpar->extradata_size = out_codec_ctx->extradata_size;
 out_stream->codecpar->extradata = static_cast(av_mallocz(out_codec_ctx->extradata_size));
 memcpy(out_stream->codecpar->extradata, out_codec_ctx->extradata, out_codec_ctx->extradata_size);

 av_dump_format(format_ctx, 0, server.c_str(), 1);

 frame = av_frame_alloc();

 int sz = av_image_get_buffer_size(pixFormat, width, height, 32);
#ifdef _WIN32
 data = (uint8_t*)_aligned_malloc(sz, 32);
 if (data == NULL)
 return ENOMEM;
#else
 ret = posix_memalign(reinterpret_cast(&data), 32, sz);
#endif
 av_image_fill_arrays(frame->data, frame->linesize, data, pixFormat, width, height, 32);
 frame->format = pixFormat;
 frame->width = width;
 frame->height = height;
 frame->pts = 1;
 if (avformat_write_header(format_ctx, nullptr) < 0) //Header making problems!!!
 {
 fprintf(stderr, "Could not write header!\n");
 return 1;
 }

 printf("stream time base = %d / %d \n", out_stream->time_base.num, out_stream->time_base.den);

 double inv_stream_timebase = (double)out_stream->time_base.den / (double)out_stream->time_base.num;
 printf("Init OK\n");
 /* Init phase end*/
 int dts = 0;
 int frameNo = 0;

 while (true) {
 //Fill dummy frame with something
 for (int y = 0; y < height; y++) {
 uint16_t color = ((y + frameNo) * 256) % (256 * 256);
 for (int x = 0; x < width; x++) {
 data[x+y*width] = color;
 }
 }

 memcpy(frame->data[0], data, 1280 * 720 * sizeof(uint16_t));
 AVPacket* pkt = av_packet_alloc();

 int ret = avcodec_send_frame(out_codec_ctx, frame);
 if (ret < 0)
 {
 fprintf(stderr, "Error sending frame to codec context!\n");
 return ret;
 }
 while (ret >= 0) {
 ret = avcodec_receive_packet(out_codec_ctx, pkt);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 break;
 else if (ret < 0) {
 fprintf(stderr, "Error during encoding\n");
 break;
 }
 pkt->dts = dts;
 pkt->pts = dts;
 dts += 33;
 av_write_frame(format_ctx, pkt);
 frameNo++;
 av_packet_unref(pkt);
 }
 printf("Streamed %d frames\n", frameNo);
 }
 return 0;
}


And part of server that should receive. code where is stops and waits


extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavformat></libavformat>avio.h>
}

int main() {
 AVFormatContext* fmt_ctx = NULL;
 av_log_set_level(AV_LOG_VERBOSE);
 AVDictionary* options = nullptr;
 av_dict_set(&options, "protocol_whitelist", "file,udp,rtp,tcp,rtmp,rtsp,hls", 0);
 av_dict_set(&options, "timeout", "500000", 0); // Timeout in microseconds 

//Next Line hangs 
 int ret = avformat_open_input(&fmt_ctx, "rtmp://localhost:9999/stream/stream1", NULL, &options);
 if (ret != 0) {
 fprintf(stderr, "Could not open RTMP stream\n");
 return -1;
 }

 // Find the first video stream
 ret = avformat_find_stream_info(fmt_ctx, nullptr);
 if (ret < 0) {
 return ret;
 }
 //...
} 



Edit :
I tried to just create a animated png and tried to stream that from the console to another console window to avoid any programming mistakes on my side. It was the same, I just could not get 16 PNG encoded stream to work. I hung trying to receive and closed when the file ended with in total zero frames received.


I managed to get other thing working :
To not encode gray frames with YUV420, I installed ffmpeg with libx264 support (was thinking is the same as H264, which in code is, but it adds support to new pixel formats). Used H264 again but with GRAY8 with doubled image width and reconstructing the image on the other side.


Maybe as a side note, I could not get any other formats to work. Is "flv" the only option here ? Could I get more performance if I changed it to... what ?


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libavcodec : Implementation of AAC_fixed_decoder (LC-module) [4/4]
30 juin 2015, par Jovan Zelinceviclibavcodec : Implementation of AAC_fixed_decoder (LC-module) [4/4]
Build system modified
There are several warnings occurring during build after this patch is
applied. The cause of most of these warnings is in that some definitions
needed here are logical part of sbr module and are added in later patches.
When this patches are applied these warnings stop occurring.The only warning that is added here and is not fixed with later patches
is warning that warns that type mismatch for table ff_aac_eld_window_480.The reason for this warning is in that ER AAC ELD 480 is not integrated in
to the fixed point implementation at this moment and there is no fixed point
version of this table.Signed-off-by : Nedeljko Babic <nedeljko.babic@imgtec.com>
Signed-off-by : Michael Niedermayer <michaelni@gmx.at> -
Revision 30797 : On passe en version 0.6 avec tout le code revu et plus ou moins corrigé
10 août 2009, par kent1@… — LogOn passe en version 0.6 avec tout le code revu et plus ou moins corrigé
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