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How to use ffmpeg for streaming mp4 via websocket
18 mai 2021, par curtissI've written a sample in nodejs which streams some input to the client via websocket connection in mp4 format. On the client side, the mp4 packages are added to a MediaSourceBuffer.
This runs fine, but only if the client gets the stream from the beginning with the first package. So another client can't play the current Stream, because he won't get the Stream from the beginning.
I tried (try&error) to save the first package ffmpeg sends and send this at the beginning of a new connection, then the current stream. Then the MediaSourceBuffer breaks because of encoding error..
Here is the ffmpeg command :
-i someInput -g 59 -vcodec libx264 -profile:v baseline -f mp4 -movflags empty_moov+omit_tfhd_offset+frag_keyframe+default_base_moof -reset_timestamps 1 -The part "empty_moov+omit_tfhd_offset+frag_keyframe+default_base_moof" should make the Streampackages independent in putting the moovatom at the beginning of each part and sizing the parts in 59 frames each by keyframe, so I don't get it why I can't view the Stream beginning after the start.
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Error initializing output stream ffmpeg on Rasbpi converting jpg to video
5 avril 2021, par JakeI have a folder with thousands of jpgs at 1024x768 that I want to convert into a single video for playback.
The error I get is
Error initializing output stream 73:0 -- Error while opening encoder for output stream #73:0 - maybe incorrect parameters such as bit_rate, rate, width or height Conversion failed!Here's my input
$ ffmpeg -i Timelapse/*.jpg -c:v libx264 -preset ultrafast -crf 0 output.mkv -yWhat is strange is it errors on a specific numbered output stream. It seems to be either 71:0, 72:0, or 73:0. I thought it was something wrong with the file it is attempting to process in the given stream but the resolution is all the same (as I've seen errors when its not divisible by 2). I've deleted the 71st-73rd image in hopes it was somehow messed up but that doesn't help either. I've ensured my libx264 is installed correctly as well.
Any suggestions?
Terminal output example
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Why is ffmpeg transcoding speed going down over time ?
24 mars 2021, par Nikola R.I'm executing basic ffmpeg command to transcode input MP4 video to output MP4 video (both using H264 as video codec, and stripping out audio, for simplicity):
ffmpeg -i input-video.mp4 -b:v 20000k -an -vcodec libx264 output-video.mp4Transcoding is initially pretty fast (around 60-70 fps for first 20 or so frames), and then starts dropping steadily, ending at around 30 fps after 5000 frames.
Is this inherent behavior? If so, why does it happen? Also, is there any better option for the command line that would improve speed (besides using -threads)?
Would it be better to cut the input video and process it as smaller chunks, getting overall higher speed per sequence? (I'm afraid that chunking might affect encoder's RD optimization)
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Creating a video from images using ffmpeg libav and libx264 ?
8 mars 2021, par marikanerI am trying to create a video from images using the ffmpeg library. The images have a size of 1920x1080 and are supposed to be encoded with H.264 using a .mkv container. I have come across various problems, thinking I am getting closer to a solution, but this one I am really stuck on. With the settings I use, the first X frames (around 40, depending on what and how many images I use for the video) of my video are not encoded. avcodec_encode_video2 does not return any error (return value is 0) with got_picture_ptr = 0. The result is a video that actually looks as expected, but the first seconds are weirdly jumpy.
So this is how I create the video file:
// m_codecContext is an instance variable of type AVCodecContext * // m_formatCtx is an instance variable of type AVFormatContext * // outputFileName is a valid filename ending with .mkv AVOutputFormat *oformat = av_guess_format(NULL, outputFileName, NULL); if (oformat == NULL) { oformat = av_guess_format("mpeg", NULL, NULL); } // oformat->video_codec is AV_CODEC_ID_H264 AVCodec *codec = avcodec_find_encoder(oformat->video_codec); m_codecContext = avcodec_alloc_context3(codec); m_codecContext->codec_id = oformat->video_codec; m_codecContext->codec_type = AVMEDIA_TYPE_VIDEO; m_codecContext->gop_size = 30; m_codecContext->bit_rate = width * height * 4 m_codecContext->width = width; m_codecContext->height = height; m_codecContext->time_base = (AVRational){1,frameRate}; m_codecContext->max_b_frames = 1; m_codecContext->pix_fmt = AV_PIX_FMT_YUV420P; m_formatCtx = avformat_alloc_context(); m_formatCtx->oformat = oformat; m_formatCtx->video_codec_id = oformat->video_codec; snprintf(m_formatCtx->filename, sizeof(m_formatCtx->filename), "%s", outputFileName); AVStream *videoStream = avformat_new_stream(m_formatCtx, codec); if(!videoStream) { printf("Could not allocate stream\n"); } videoStream->codec = m_codecContext; if(m_formatCtx->oformat->flags & AVFMT_GLOBALHEADER) { m_codecContext->flags |= CODEC_FLAG_GLOBAL_HEADER; } avcodec_open2(m_codecContext, codec, NULL) < 0); avio_open(&m_formatCtx->pb, outputFileName.toStdString().c_str(), AVIO_FLAG_WRITE); avformat_write_header(m_formatCtx, NULL);this is how the frames are added:
void VideoCreator::writeImageToVideo(const QSharedPointer&img, int frameIndex) { AVFrame *frame = avcodec_alloc_frame(); /* alloc image and output buffer */ int size = m_codecContext->width * m_codecContext->height; int numBytes = avpicture_get_size(m_codecContext->pix_fmt, m_codecContext->width, m_codecContext->height); uint8_t *outbuf = (uint8_t *)malloc(numBytes); uint8_t *picture_buf = (uint8_t *)av_malloc(numBytes); int ret = av_image_fill_arrays(frame->data, frame->linesize, picture_buf, m_codecContext->pix_fmt, m_codecContext->width, m_codecContext->height, 1); frame->data[0] = picture_buf; frame->data[1] = frame->data[0] + size; frame->data[2] = frame->data[1] + size/4; frame->linesize[0] = m_codecContext->width; frame->linesize[1] = m_codecContext->width/2; frame->linesize[2] = m_codecContext->width/2; fflush(stdout); for (int y = 0; y < m_codecContext->height; y++) { for (int x = 0; x < m_codecContext->width; x++) { unsigned char b = img->bits()[(y * m_codecContext->width + x) * 4 + 0]; unsigned char g = img->bits()[(y * m_codecContext->width + x) * 4 + 1]; unsigned char r = img->bits()[(y * m_codecContext->width + x) * 4 + 2]; unsigned char Y = (0.257 * r) + (0.504 * g) + (0.098 * b) + 16; frame->data[0][y * frame->linesize[0] + x] = Y; if (y % 2 == 0 && x % 2 == 0) { unsigned char V = (0.439 * r) - (0.368 * g) - (0.071 * b) + 128; unsigned char U = -(0.148 * r) - (0.291 * g) + (0.439 * b) + 128; frame->data[1][y/2 * frame->linesize[1] + x/2] = U; frame->data[2][y/2 * frame->linesize[2] + x/2] = V; } } } int pts = frameIndex;//(1.0 / 30.0) * 90.0 * frameIndex; frame->pts = pts;//av_rescale_q(m_codecContext->coded_frame->pts, m_codecContext->time_base, formatCtx->streams[0]->time_base); //(1.0 / 30.0) * 90.0 * frameIndex; int got_packet_ptr; AVPacket packet; av_init_packet(&packet); packet.data = outbuf; packet.size = numBytes; packet.stream_index = formatCtx->streams[0]->index; packet.flags |= AV_PKT_FLAG_KEY; packet.pts = packet.dts = pts; m_codecContext->coded_frame->pts = pts; ret = avcodec_encode_video2(m_codecContext, &packet, frame, &got_packet_ptr); if (got_packet_ptr != 0) { m_codecContext->coded_frame->pts = pts; // Set the time stamp if (m_codecContext->coded_frame->pts != (0x8000000000000000LL)) { pts = av_rescale_q(m_codecContext->coded_frame->pts, m_codecContext->time_base, formatCtx->streams[0]->time_base); } packet.pts = pts; if(m_codecContext->coded_frame->key_frame) { packet.flags |= AV_PKT_FLAG_KEY; } std::cout << "pts: " << packet.pts << ", dts: " << packet.dts << std::endl; av_interleaved_write_frame(formatCtx, &packet); av_free_packet(&packet); } free(picture_buf); free(outbuf); av_free(frame); printf("\n"); } and this is the cleanup:
int numBytes = avpicture_get_size(m_codecContext->pix_fmt, m_codecContext->width, m_codecContext->height); int got_packet_ptr = 1; int ret; // for(; got_packet_ptr != 0; i++) while (got_packet_ptr) { uint8_t *outbuf = (uint8_t *)malloc(numBytes); AVPacket packet; av_init_packet(&packet); packet.data = outbuf; packet.size = numBytes; ret = avcodec_encode_video2(m_codecContext, &packet, NULL, &got_packet_ptr); if (got_packet_ptr) { av_interleaved_write_frame(m_formatCtx, &packet); } av_free_packet(&packet); free(outbuf); } av_write_trailer(formatCtx); avcodec_close(m_codecContext); av_free(m_codecContext); printf("\n");I assume it might be tied to the PTS and DTS values, but I have tried EVERYTHING. The frame index seems to make the most sense. The images are correct, I can save them to files without any problems. I am running out of ideas. I would be incredibly thankful if there was someone out there who knew better than me...
Cheers, marikaner
UPDATE:
If this is of any help this is the output at the end of the video encoding:
[libx264 @ 0x7fffc00028a0] frame I:19 Avg QP:14.24 size:312420 [libx264 @ 0x7fffc00028a0] frame P:280 Avg QP:19.16 size:148867 [libx264 @ 0x7fffc00028a0] frame B:181 Avg QP:21.31 size: 40540 [libx264 @ 0x7fffc00028a0] consecutive B-frames: 24.6% 75.4% [libx264 @ 0x7fffc00028a0] mb I I16..4: 30.9% 45.5% 23.7% [libx264 @ 0x7fffc00028a0] mb P I16..4: 4.7% 9.1% 4.5% P16..4: 23.5% 16.6% 12.6% 0.0% 0.0% skip:28.9% [libx264 @ 0x7fffc00028a0] mb B I16..4: 0.6% 0.5% 0.3% B16..8: 26.7% 11.0% 5.5% direct: 3.9% skip:51.5% L0:39.4% L1:45.0% BI:15.6% [libx264 @ 0x7fffc00028a0] final ratefactor: 19.21 [libx264 @ 0x7fffc00028a0] 8x8 transform intra:48.2% inter:47.3% [libx264 @ 0x7fffc00028a0] coded y,uvDC,uvAC intra: 54.9% 53.1% 30.4% inter: 25.4% 13.5% 4.2% [libx264 @ 0x7fffc00028a0] i16 v,h,dc,p: 41% 29% 11% 19% [libx264 @ 0x7fffc00028a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 26% 31% 3% 4% 3% 7% 3% 6% [libx264 @ 0x7fffc00028a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 30% 26% 14% 4% 5% 4% 7% 4% 7% [libx264 @ 0x7fffc00028a0] i8c dc,h,v,p: 58% 26% 13% 3% [libx264 @ 0x7fffc00028a0] Weighted P-Frames: Y:17.1% UV:3.6% [libx264 @ 0x7fffc00028a0] ref P L0: 63.1% 21.4% 11.4% 4.1% 0.1% [libx264 @ 0x7fffc00028a0] ref B L0: 85.7% 14.3% [libx264 @ 0x7fffc00028a0] kb/s:27478.30 -
Convert .mp4 to .ts using H264 at constant framerate 25fps [closed]
4 mars 2021, par losing-my-marblesI've been trying to do this conversion for a couple of days reading through forums
ffmpeg -i in1.mp4 -vcodec libx264 -s 720x576 -vf "fps=25"-vsync cfr -b:v 2300k -acodec aac -b:a 128k out1.tsI've tried the below flags found in other forums.
... -r 25 -vf fps=25 -filter:v fps=25 -filter:v fps=fps=25I then read the file using mediainfo and keep getting the same result;
Frame rate mode : VFR Frame rate mode : Variable Frame rate : 46.875 Frame rate : 46.875 FPS (1024 SPF)
