Recherche avancée

Sur d’autres sites (9316)

• FFMPEG MKV -> MP4 Batch Conversion

  15 juillet 2024, par blaziken386

  I'm trying to write a program that lets me convert a series of .mkv files with subtitle files into .mp4 files with the subs hardcoded.

  


  Right now, the script I use is

  


  ffmpeg -i input.mkv -vf subtitles=input.mkv output.mp4



  


  This is fine, but it means I can only convert them one at a time, and it's kind of a hassle because it means I have to fiddle with it every few minutes to set up the next one.

  


  I have another script I use for converting .flac files to .mp3 files, which is

  


  @ECHO OFF

FOR %%f IN (*.flac) DO (
echo Converting: %%f
ffmpeg -i "%%f" -ab 320k -map_metadata 0 "%%~nf.mp3"
)

echo Finished

PAUSE



  


  Running that converts every single .flac folder into an .mp3 equivalent, with the same filename and everything.

  


  I've tried to combine the above scripts into something like this :

  


  @ECHO OFF

FOR %%f IN (*.mkv) DO (
echo Converting: %%f
ffmpeg -i "%%f" -vf subtitles=%%f "%%~nf.mp4"
)

echo Finished

PAUSE


  


  but every time I do so, it returns errors like "invalid argument" or "unable to find a suitable output type", or "error initializing filters", or "2 frames left in the queue on closing" or something along those lines. I've swapped out subtitles=%%f for "subtitles-%%f" or subtitles="%%f.mkv" and so on and so forth, and none of those give me what I want either. Sometimes it creates Empty .mp4 file containers with nothing in them, sometimes it does nothing at all.

  


  I don't really understand what exactly is happening under the hood in that flac->mp3 code, because I grabbed it from a different stackoverflow post years ago. All I know is that trying to copy that code and repurpose it into something else doesn't work. Is this just an issue where I've fucked up the formatting of the code and not realized it, or is this a "ffmpeg can't actually do that because of a weird technical issue" thing ?

  


  I also tried the code listed here, when Stackoverflow listed that as a possible duplicate, but that gave me similar errors, and I don't really understand why !

  


  Also, if it's relevant, I'm running windows.

  


• Construct fictitious P-frames from just I-frames [closed]

  25 juillet 2024, par nilgirian

  Some context.. I saw this video recently https://youtu.be/zXTpASSd9xE?si=5alGvZ_e13w0Ahmb it's a continuous zoom into a fractal.

  


  I've been thinking a whole lot of how did they created this video 9 years ago ? The problem is that these frames are mathematically intensive to calculate back then and today still fairly really hard now.

  


  He states in the video it took him 33 hours to generate 1 keyframe.

  


  I was wondering how I would replicate that work. I know by brute force I can generate several images files (essentially each image would be an I-frame) and then ask ffmpeg to compress it into mp4 (where it will convert most of those images into P-frames). I know that. But if I did it that way I calculated it'd take me 6.5 years to render that 9min video (at 30fps, 9 years ago).

  


  So I imagine he only generated I-frames to cut down on time. And then this person somehow created fictitious P-frames in-between. Given that frame-to-frame are similar this seems like it should be doable since you're just zooming in. If he only generated just the I-frames at every 1 second (at 30fps) that work could be cut down to just 82 days.

  


  So if I only want to generate the images that will be used as I-frames could ffmpeg or some other program just automatically make a best guess to generate fictitious P-frames for me ?

  


• lavu/riscv : grok B as an extension

  22 juillet 2024, par Rémi Denis-Courmont

  lavu/riscv : grok B as an extension
  The RISC-V B bit manipulation extension was ratified only two months ago.
  
  But it is strictly equivalent to the union of the zba, zbb and zbs
  
  extensions which were defined almost 3 years earlier. Rather than require
  
  new assembler, we can just match the extension name manually and translate
  
  it into its constituent parts.
  

  • [DH] libavutil/riscv/asm.S