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• encoding a video to AV1 for compression

  24 mars, par living being

  I wrote a code to encode a 1080p video to AV1 codec to reduce the file size. At the same time, I encoded the same video to x265. As they say, AV1 should reduce the size around 40-50% more than x265. But I didn't achieve it.

  


  The original file size : 74 MB

  


  the file encoded with AV1 : 53 MB

  


  The file encoded with x265 : 34 MB

  


  My AV1 code :

  


  ffmpeg -i "input.webm" -vcodec libsvtav1 -preset 4 -crf 38 -acodec libopus -ac 1 -b:a 24K "output.mkv";

  


  My x265 code :

  


  ffmpeg -i "input.webm" -vcodec libx265 -preset fast -crf 31 -acodec libopus -ac 1 -b:a 24K "output.mkv";

  


  I used a higher CRF for AV1 code to get a smaller file, but it didn't work.
What's wrong with my AV1 code ?

  


  I used different input files and got similar results. My OS : Ubuntu 24.10

  


• How to Record a Seekable Video File with Lossless Compression which is seekable while recording ? [closed]

  21 novembre 2024, par Christian Schaffner

  I am using FFmpeg to record a dshow device to a .mkv file. My goal is to use a lossless codec like H.264 or FFV1 for the best quality. Here’s the issue I’m encountering :

  


  In my application, the recorded file needs to be played in another application while recording is still in progress. While playback works, the file is not seekable because the index is written only after the recording ends.

  


  My question :
  
Is there any way to record a video that remains seekable, even if the recording process is incomplete ? I am open to low-filesize, uncompressed formats or other practical solutions that meet these requirements.

  


  Here’s my current FFmpeg command :

  


  ffmpeg -f dshow -i video="Your Video Device" -c:v libx264 -preset ultrafast -crf 0 output.mkv

  


  I've also tried FFV1 as the codec, but the seekability issue persists :

  


  ffmpeg -f dshow -i video="Your Video Device" -c:v ffv1 output.mkv

  


  Things I’ve Tried :

  


  

  1. Using the -movflags +faststart option (applicable to MP4, but not for MKV).

  


  2. Switching container formats to see if other containers might write the index during recording (e.g., AVI or MP4).

  


  3. Exploring streaming protocols (e.g., udp or rtmp) for playback but found these unsuitable for my use case.

  


  


  Requirements :

  


  

  • Lossless video quality (e.g., H.264 lossless or FFV1).

  


  • Seekable playback during recording.

  


  


  Examples

  


  

  1. How to record a seekable H.264 lossless video while still recording ?

  


  2. Can FFV1 (or similar codecs) support live seekable playback during recording ?

  


  


  Does FFmpeg or any container format have a feature or flag that could solve this problem ? Or are there alternative workflows or tools that can help ? Any help or suggestions would be appreciated !

  


  EDIT :
The Reading application uses PyAV which intern uses FFMEG.

  


• How to Record a Seekable Video File with Lossless Compression wich is seekable while recording ?

  21 novembre 2024, par Christian Schaffner

  I am using FFmpeg to record a dshow device to a .mkv file. My goal is to use a lossless codec like H.264 or FFV1 for the best quality. Here’s the issue I’m encountering :

  


  In my application, the recorded file needs to be played in another application while recording is still in progress. While playback works, the file is not seekable because the index is written only after the recording ends.

  


  My question :
  
Is there any way to record a video that remains seekable, even if the recording process is incomplete ? I am open to low-filesize, uncompressed formats or other practical solutions that meet these requirements.

  


  Here’s my current FFmpeg command :

  


  ffmpeg -f dshow -i video="Your Video Device" -c:v libx264 -preset ultrafast -crf 0 output.mkv

  


  I've also tried FFV1 as the codec, but the seekability issue persists :

  


  ffmpeg -f dshow -i video="Your Video Device" -c:v ffv1 output.mkv

  


  Things I’ve Tried :

  


  

  1. Using the -movflags +faststart option (applicable to MP4, but not for MKV).

  


  2. Switching container formats to see if other containers might write the index during recording (e.g., AVI or MP4).

  


  3. Exploring streaming protocols (e.g., udp or rtmp) for playback but found these unsuitable for my use case.

  


  


  Requirements :

  


  

  • Lossless video quality (e.g., H.264 lossless or FFV1).

  


  • Seekable playback during recording.

  


  


  Examples

  


  

  1. How to record a seekable H.264 lossless video while still recording ?

  


  2. Can FFV1 (or similar codecs) support live seekable playback during recording ?

  


  


  Does FFmpeg or any container format have a feature or flag that could solve this problem ? Or are there alternative workflows or tools that can help ? Any help or suggestions would be appreciated !

  


  EDIT :
The Reading aplication uses PyAV wich intern uses FFMEG.