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• Audio delay after resuming FFmpeg on Windows

  27 mars, par Iman Sajadpur

  I'm building a screen recording software for Windows using Python. I use FFmpeg for recording and psutil to pause and resume the process.

  


  Here is a sample of my code :

  


  import psutil
import subprocess

process = subprocess.Popen([
        'ffmpeg', '-y',
        '-rtbufsize', '100M',
        '-f', 'gdigrab',
        '-thread_queue_size', '1024',
        '-probesize', '50M',
        '-r', '24',
        '-draw_mouse', '1',
        '-video_size', '1920x1080',
        '-i', 'desktop', 
        '-f', 'dshow',
        '-channel_layout', 'stereo',
        '-thread_queue_size', '1024',
        '-i', 'audio=Microphone (2- High Definition Audio Device)', # my audio device
        '-c:v', 'h264_nvenc', # encoding via Nvidia
        '-r', '24',
        '-preset', 'p1',
        '-pix_fmt', 'yuv444p',
        '-fps_mode', 'cfr',
        '-c:a', 'aac', 
        '-ac', '2',
        '-b:a', '128k',
        'output.mp4'])

ffmpeg_proc = psutil.Process(process.pid)

# pause
ffmpeg_proc.suspend()

# resume
ffmpeg_proc.resume() 


  


  The issue is that after resuming, the audio becomes choppy and delayed, while the video continues smoothly.

  


  I have tried using following flags, but they didn't solve the issue :

  


  -analyzeduration
-fflags +genpts
-async
-use_wallclock_as_timestamps
-af aresample=async=1


  


  How can I properly pause and resume FFmpeg without causing audio delay ?
Is there any other method to handle this properly ?

  


  Thanks for any suggestions.

  


• Back porting ffmpeg.dll from electron for windows xp by disassembling

  28 juillet 2024, par Oosuke Ren

  I've recently gotten into a really interesting project of having a fully functional (and as futuristic as possible) physical retro gaming machine with windows xp. I had found One Core Api that successfully works to allow for some programs to work that otherwise wouldn't have. One of them is electron (5.0.13). Thanks to a vast testing between a VM with the kernel extender and a vanilla XP, I found out that the only thing stopping me from succeeding is because it's dependent on an EXTREMELY specific version/fork of ffmpeg (Chromium fork of ffmpeg 4.1) . Due to that being a relatively old fork/version, the build tools/links for some of the stuff are nonexistent right now, so even if I do have the fork locally with all the instructions, I can't build it. (and if I do I have to patch Win Vista+ Api functions, with one custom stub dll I have)

  


  AcquireSRWLockExclusive InitializeConditionVariable SleepConditionVariableSRW InitOnceBeginInitialize InitOnceComplete InitializeSRWLock ReleaseSRWLockExclusive WakeAllConditionVariable WakeConditionVariable

  


  Since I can't custom build ffmpeg I have to patch it's calls by redirecting them to my custom dll that includes these back ported functions and more.

  


  I tried many different ways => IDA Pro, Ghidra, objconv, currently am the closest with "DLL to C"

  


  Ida Pro and Ghidra seem to not be creating assembly code that I'd be able to assemble back after patching.

  


  objconv produces a really accurate disassembly, but the issue is it doesn't have an assembler. And the produced .asm won't assemble with Fasm, masm or nasm

  


  As for DLL to C-> successfully created a quite presentable VS project, the project successfully compiles with only one warning, the byte sizes is quite similar, the problem is => the functions are getting wrongly directed (towards wrong functions in my dll- and thus the ones needed are undefined) And this is too deep to be able to tell if it's a VS version issue, wrong code implementation or if just DLL to C has wrongly disassembled the logic.

  


  Question is, is my last option remaining to manually edit the HEXES of the Import Address Table and Import Names so they get redirected ? (the problem is my knowledge in Assembly isn't too good, so I'm not sure if that's all I'd have to do, and even if so, I have a feeling I'd mess up the Virtual Addresses or something.

  


• FFmpegInteropX in Unity Hololens 2

  25 juin 2024, par CocoaMilka

  I'm building a UDP video stream decoder for the Hololens 2 in Unity 2021. I've compiled FFmpegInteropX for ARM64 UWP, however I'm having issues setting it up within Unity. With the binaries included in /Plugins/WSA I get the following error :

  


  ArgumentException: The Assembly WinRT.Runtime is referenced by FFmpegInteropX.DotNet ('Assets/Plugins/WSA/FFmpegInteropX.DotNet/Release/FFmpegInteropX.DotNet.dll'). But the dll is not allowed to be included or could not be found.

  


  I've wrapped all of my WinRT dependent code with the appropriate preprocessor directive as shown here, and I've also set all my plugins to target WSAPlayer and UWP.

  


  #if ENABLE_WINMD_SUPPORT
using FFmpegInteropX;
using WinRT;
using Windows.Foundation;
using Windows.Media.Core;
using Windows.Media.Playback;
using System.Threading.Tasks;
#endif


  


  If I include WinRT.Runtime.dll in the plugins folder, the issue spreads asking for more dependencies then the new dependencies (such as Microsoft.Windows.SDK.NET.dll) starts conflicting with the MRTK packages due to it also depending on WinRT.

  


  How can I use this library within Unity without constantly running into dependency hell ?