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• What are my FFMPEG command wrong parameters that causes ugly quality on streaming ?

  6 juillet 2022, par Lucas FAURE

  Good day, I'm scaling videos with FFMPEG, and when the scaled file comes out, quality is pretty good (enough good for me).

  


  My problem is that I'm as well streaming the file while it's scaling, but it comes in an ugly quality. And I guess it's because of missing or not needed parameters.

  


  Here is my command that starts scaling the file and send it via RTMP for streaming :

  


  "ffmpeg -i " + file + " -vf scale=-2:" + resolution + " -preset slow -crf 18 -movflags +frag_keyframe+separate_moof+omit_tfhd_offset+empty_moov " + output + " -listen 1 -f flv rtmp://127.0.0.1:10000/" + stream + ""


  


  This is called in Python, where file is the source file, resolution the new height, output the file to be saved, and stream a streaming key.

  


  Once the scaling has started, I provide to the user a streaming link with the new resolution :

  


  'ffmpeg -v verbose -i rtmp://127.0.0.1:10000/'.$stream.' -c:v libx264 -c:a aac -ac 1 -strict -2 -crf 18 -profile:v baseline -maxrate 400k -bufsize 1835k -pix_fmt yuv420p -flags -global_header -hls_time 10 -hls_list_size 6 -start_number 1 '.$streamURL.$stream;


  


  Here, it's called with PHP, and there are as well variables : stream the streaming key to retreive the right content, and streamURL the domain to visit.

  


  It actually works but the difference of quality between what is scaling and what is streaming is huge, and I think so that, in the command that creates the streaming link, there is parameters that cause this. (Because I took it from a live example and I didn't want to make an error by removing parameters I don't know well)

  


  Do you have any idea about where it can be coming from ?

  


  Thank you in advance for your help and time.

  


• Why are v0, v1, and v2 of ffmpeg still under active development ? What happened to ppa:jon-severinsson/ffmpeg ?

  12 avril 2015, par cxrodgers

  I know about the long history of ffmpeg and libav. Personally, I preferred to use Jon Severinsson’s PPA, as suggested in many answers here on stackoverflow or askubuntu. However, recently this PPA seems to have gone down recently (this page, which is the link everyone always gives, is dead). I don’t see if he put up a newer version, although I admit I find launchpad hard to navigate. Did it get replaced with this one from Doug McMahon or this one from Sam Rog ?

  Ok, so maybe I need to download it myself. I visit the releases page for ffmpeg, and there seems to be simultaneous development of releases from v2 (2.6.2), v1 (1.2.12, from February), and v0 (0.10.16, from March of this year). 0.10 isn’t even the newest of the v0 series, and yet it seems to be the most recently updated of that series, and (coincidentally ?) also the version that I most recently got from the PPA. Admittedly this was on a slightly older distribution (Linux Mint 16).

  ffmpeg -version
  
  ffmpeg version 0.10.12-7:0.10.12-1~saucy1

  So, which version should I download, now that the PPA is gone ? Does it depend on the distribution I’m using ?

• avcodec/utils : allocate a line more for VC1 and WMV3

  11 janvier 2023, par Michael Niedermayer

  avcodec/utils : allocate a line more for VC1 and WMV3
  Fixes : out of array read on 32bit
  
  Fixes : 54857/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1_fuzzer-5840588224462848
  The chroma MC code reads over the currently allocated frame.
  
  Alternative fixes would be allocating a few bytes more at the end instead of a whole
  
  line extra or to adjust the threshold where the edge emu code is activated
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/utils.c