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• Streaming Webcam Over LAN : HTML5 Video Element Not Loading

  27 novembre 2023, par Franck Freiburger

  I am currently working on a project where I aim to stream my webcam over my LAN and read the stream in an HTML5 video element with minimal setup. My setup involves a server (192.168.0.1 dev/video0 -> ffmpeg) and a client (192.168.0.2 html5 browser). I am using ffmpeg with the codec set to h264.

  


  Here is the ffmpeg command I am using :

  


  ffmpeg -f video4linux2 -i /dev/video0
  -an -c:v libx264 -b:v 1024k -video_size 800x600 -pix_fmt yuv420p -preset ultrafast
  -tune zerolatency -g 16 -keyint_min 16 -f mpegts pipe:1


  


  This command is spawned by a simple Node.js server that shares this stream without any transformation (just pipe ffpmeg stream to each incoming connection).

  


  When I use vlc or ffplay with the following command, it works very well :

  


  ffplay -fflags nobuffer -flags low_delay -probesize 32 -analyzeduration 0 -framedrop http://192.168.0.1:3000/stream


  


  I can even run multiple instances of ffplay and the video is properly played. However, when I try to use the HTML5 element like this :

  


  <video src="http://127.0.0.1:3000/stream" type="video/mp4"></video>&#xA;

  


  The video seems to "load forever" without any error, nothing suspect in chrome://media-internals. I can see in the network tab that the network is reading the stream, but the video does not play (got same result using hljs and videojs).

  


  

  


  I am looking for help to understand :

  


  

  • What is wrong with the <video></video> element in this context ?

  


  • Is there a better approach to achieve this ?

  


  


  Any help or guidance would be greatly appreciated.

  


• lavc/opusdsp : rewrite R-V V postfilter

  2 novembre 2023, par Rémi Denis-Courmont

  lavc/opusdsp : rewrite R-V V postfilter
  This uses a more traditional approach allowing up processing of up to
  
  period minus two elements per iteration. This also allows the algorithm
  
  to work for all and any vector length.
  As the T-Head C908 device under test can load 16 elements loop, there is
  
  unsurprisingly a little performance drop when the period is minimal and
  
  the parallelism is capped at 13 elements :
  Before :
  
  postfilter_15_c :         21222.2
  
  postfilter_15_rvv_f32 :   22007.7
  
  postfilter_512_c :        20189.7
  
  postfilter_512_rvv_f32 :  22004.2
  
  postfilter_1022_c :       20189.7
  
  postfilter_1022_rvv_f32 : 22004.2
  After :
  
  postfilter_15_c :         20189.5
  
  postfilter_15_rvv_f32 :    7057.2
  
  postfilter_512_c :        20189.5
  
  postfilter_512_rvv_f32 :   5667.2
  
  postfilter_1022_c :       20192.7
  
  postfilter_1022_rvv_f32 :  5667.2
  

  • [DH] libavcodec/riscv/opusdsp_init.c
  • [DH] libavcodec/riscv/opusdsp_rvv.S

• What is the ideal image format extraction for YUV color space and lossless compression from mxf video format using ffmpeg

  15 février 2016, par DragonDance27

  I would like to be able to work on frames from an .mxf video file. The image format of the video is JPEG 2000, using a YUV color space with 4:2:2 subsampling and lossless compression.

  My intentions are to extract frames from this video using ffmpeg. Extracted frames would then be processed in Matlab (at the moment I’m interested in performing colorization).

  I want to extract the frames with as minimal data loss as possible and I would like to work in the YUV color space. I understand PNG involves a lossless process, but only involves the RGB color space - so not an option.

  I think I can extract jpeg2000 frames in the YUV color space, but I’m not sure if I’m losing data from the compression process. I attempted the following code in ffmpeg :

  ffmpeg -i video.mxf -r 1/5 out%03d.jp2

  ... however, the extracted jp2 files are unreadable in various software, including HiView which is a specialised JPEG 2000 software.

  Quesiton 1 : Is this jpeg 2000 extraction method lossless ? What am I doing wrong ?

  I also considered extracting the images in the tiff format where I can achieve the YUV and lossless requirements. I attempted the following code in ffmpeg :

  ffmpeg -i video.mxf -vcodec tiff f%10d.tif

  ... however, the extracted tiff files are unreadable in software such as paint, paint.net and windows photo viewer.

  Question 2 : Is this tiff extraction method correct ? What am I doing wrong ?

  Question 3 : What is an ideal image format that covers my YUV and lossless requirements ?