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• Batch splitting large audio files into small fixed-length audio files in moments of silence

  26 juillet 2023, par Haldjärvi

  to train the SO-VITS-SVC neural network, we need 10-14 second voice files. As a material, let's say I use phrases from some game. I have already made a batch script for decoding different files into one working format, another batch script for removing silence, as well as a batch script for combining small audio files into files of 13-14 seconds (I used Python, pydub and FFmpeg). To successfully automatically create a training dataset, it remains only to make one batch script - Cutting audio files lasting more than 14 seconds into separate files lasting 10-14 seconds, cutting in places of silence or close to silence is highly preferable.

  


  So, it is necessary to batch cut large audio files (20 seconds, 70 seconds, possibly several hundred seconds) into segments of approximately 10-14 seconds, however, the main task is to look for the quietest place in the cut areas so as not to cut phrases in the middle of a word (this is not very good for model training). So, is it really possible to do this in a very optimal way, so that the processing of a 30-second file does not take 15 seconds, but is fast ? Quiet zone detection is required only in the area of cuts, that is, 10-14 seconds, if counted from the very beginning of the file.

  


  I would be very grateful for any help.

  


  I tried to write a script together with ChatGPT, but all options gave completely unpredictable results and were not even close to what I needed... I had to stop at the option with a sharp cut of files for exactly 14000 milliseconds. However, I hope there is a chance to make a variant with cutting exactly in quiet areas.

  


  import os
from pydub import AudioSegment

input_directory = ".../RemSilence/"
output_directory = ".../Split/"
max_duration = 14000

def split_audio_by_duration(input_file, duration):
    audio = AudioSegment.from_file(input_file)
    segments = []
    for i in range(0, len(audio), duration):
        segment = audio[i:i + duration]
        segments.append(segment)
    return segments

if __name__ == "__main__":
    os.makedirs(output_directory, exist_ok=True)
    audio_files = [os.path.join(input_directory, file) for file in os.listdir(input_directory) if file.endswith(".wav")]
    audio_files.sort(key=lambda file: len(AudioSegment.from_file(file)))
    for file in audio_files:
        audio = AudioSegment.from_file(file)
        if len(audio) > max_duration:
            segments = split_audio_by_duration(file, max_duration)
            for i, segment in enumerate(segments):
                output_filename = f"output_{len(os.listdir(output_directory))+1}.wav"
                output_file_path = os.path.join(output_directory, output_filename)
                segment.export(output_file_path, format="wav")
        else:
            output_filename = f"output_{len(os.listdir(output_directory))+1}.wav"
            output_file_path = os.path.join(output_directory, output_filename)
            audio.export(output_file_path, format="wav")


  


• Dreamcast Anniversary Programming

  10 septembre 2010, par Multimedia Mike — Game Hacking

  This day last year saw a lot of nostalgia posts on the internet regarding the Sega Dreamcast, launched 10 years prior to that day (on 9/9/99). Regrettably, none of the retrospectives that I read really seemed to mention the homebrew potential, which is the aspect that interested me. On the occasion of the DC’s 11th anniversary, I wanted to remind myself how to build something for the unit and do so using modern equipment and build tools.

  
  
  

  Background
  Like many other programmers, I initially gained interest in programming because I desired to program video games. Not content to just plunk out games on a PC, I always had a deep, abiding ambition to program actual video game hardware. That is, I wanted to program a purpose-built video game console. The Sega Dreamcast might be the most ideal candidate to ever emerge for that task. All that was required to run your own software on the unit was the console, a PC, some free software tools, and a special connectivity measure.

  The Equipment
  Here is the hardware required (ideally) to build software for the DC :

  • The console itself (I happen to have 3 of them laying around, as pictured above)
  • Some peripherals : Such as the basic DC controller, the DC keyboard (flagship title : Typing of the Dead), and the visual memory unit (VMU)
    
    
    
  • VGA box : The DC supported 480p gaming via a device that allowed you to connect the console straight to a VGA monitor via 15-pin D-sub. Not required for development, but very useful. I happen to have 3 of them from different third parties :
    
    
    
  • Finally, the connectivity measure for hooking the DC to the PC.
    There are 2 options here. The first is rare, expensive and relatively fast : A DC broadband adapter. The second is slower but much less expensive and relatively easy to come by– the DC coder’s cable. This was a DB-9 adapter on one end and a DC serial adapter on the other, and a circuit in the middle to monkey with voltage levels or some such ; I’m no electrical engineer. I procured this model from the notorious Lik Sang, well before that outfit was sued out of business.
    
    
    

  Dealing With Legacy
  Take a look at that coder’s cable again. DB-9 ? When was the last time you owned a computer with one of those ? And then think farther back to the last time to had occasion to plug something into one of those ports (likely a serial mouse).

  
  
  

  A few years ago, someone was about to toss out this Belkin USB to DB-9 serial converter when I intervened. I foresaw the day when I would dust off the coder’s cable. So now I can connect a USB serial cable to my Eee PC, which then connects via converter to a different serial cable, one which has its own conversion circuit that alters the connection to yet another type of serial cable.

  Bits is bits is bits as far as I’m concerned.

  
  
  

  Putting It All Together
  Now to assemble all the pieces (plus a monitor) into one development desktop :

  
  
  

  The monitor says “dcload 1.0.3, idle…”. That’s a custom boot CD-ROM that is patiently waiting to receive commands, code and data via the serial port.

  Getting The Software
  Back in the day, homebrew software development on the DC revolved around these components :

  • GNU binutils : for building base toolchains for the Hitachi SH-4 main CPU as well as the ARM7-based audio coprocessor
  • GNU gcc/g++ : for building compilers on top of binutils for the 2 CPUs
  • Newlib : a C library intended for embedded systems
  • KallistiOS : an open source, real-time OS developed for the DC

  The DC was my first exposure to building cross compilers. I developed some software for the DC in the earlier part of the decade. Now, I am trying to figure out how I did it, especially since I think I came up with a few interesting ideas at the time.

  Struggling With the Software Legacy
  The source for KallistiOS has gone untouched since about 2004 but is still around thanks to Sourceforge. The instructions for properly building the toolchain have been lost to time, or would be were it not for the Internet Archive’s copy of a site called Hangar Eleven. Also, KallistiOS makes reference to a program called ‘dc-tool’ which is needed on the client side for communicating with dcload. I was able to find this binary at the Boob ! site (well-known in DC circles).

  I was able to build the toolchain using binutils 2.20.1, gcc 4.5.1 and newlib 1.18.0. Building the toolchain is an odd process as it requires building the binutils, then building the C compiler, then newlib, and then building the C compiler again along with the C++ compiler because the C++ compiler depends on newlib.

  With some effort, I got the toolchain to build KallistiOS and most of its example programs. I documented most of the tweaks I had to make, several of them exactly the same as this one that I recently discovered while resurrecting a 10-year-old C program (common construct in C programming of old ?).

  Moment of Truth
  So I had some example programs built as ELF files. I told dc-tool to upload and run them on the waiting console. Unfortunately, the tool would just sort of stall, though some communication had evidently taken place. It has been many years since I have seen this in action but I recall that something more ought to be happening.

  Plan B (Hardware)
  This is the point that I remember that I have been holding onto one rather old little machine that still has a DB-9 serial port. It’s not especially ergonomic to set up. I have to run it on my floor because, to connect it to my network, I need to run a 25′ ethernet cable that just barely reaches from the other room. The machine doesn’t seem to like USB keyboards, which is a shame since I have long since ditched any PS/2 keyboards. Fortunately, the box still has an old Gentoo distro and is running sshd, a holdover from its former life as a headless box.

  
  
  

  Now when I run dc-tool, both the PC and DC report the upload progress while pretty overscan bars oscillate on the DC’s monitor. Now I’m back in business, until…

  Plan C (Software)
  None of these KallistiOS example programs are working. Some are even reporting catastrophic failures (register dumps) via the serial console. That’s when I remember that gcc can be a bit fickle on CPU architectures that are not, shall we say, first-class citizens. Back in the day, gcc 2.95 was a certified no-go for SH-4 development. 3.0.3 or 3.0.4 was called upon at the time. As I’m hosting this toolchain on x86_64 right now, gcc 3.0.4 can’t even be built (predates the architecture).

  One last option : As I searched through my old DC project directories, I found that I still have a lot of the resulting binaries, the ones I built 7-8 years ago. I upload a few of those and I finally see homebrew programming at work again, including this old program (described in detail here).

  Next Steps
  If I ever feel like revisiting this again, I suppose I can try some of the older 4.x series to see if they build valid programs. Alternatively, try building an x86_32-hosted 3.0.4 toolchain which ought to be a known good. And if that fails, search a little bit more to find that there are still active Dreamcast communities out there on the internet which probably have development toolchain binaries ready for download.

• Unity : Converting Texture2D to YUV420P using FFmpeg

  23 juillet 2021, par strong_kobayashi

  I'm trying to create a game in Unity where each frame is rendered into a texture and then put together into a video using FFmpeg. The output created by FFmpeg should eventually be sent over the network to a client UI. However, I'm struggling mainly with the part where a frame is caught, and passed to an unsafe method as a byte array where it should be processed further by FFmpeg. The wrapper I'm using is FFmpeg.AutoGen.

  



  The render to texture method :

  



  private IEnumerator CaptureFrame()
{
    yield return new WaitForEndOfFrame();

    RenderTexture.active = rt;
    frame.ReadPixels(rect, 0, 0);
    frame.Apply();

    bytes = frame.GetRawTextureData();

    EncodeAndWrite(bytes, bytes.Length);
}


  



  The unsafe encoding method so far :

  



  private unsafe void EncodeAndWrite(byte[] bytes, int size)
{
    GCHandle pinned = GCHandle.Alloc(bytes, GCHandleType.Pinned);
    IntPtr address = pinned.AddrOfPinnedObject();

    sbyte** inData = (sbyte**)address;
    fixed(int* lineSize = new int[1])
    {
        lineSize[0] = 4 * textureWidth;
        // Convert RGBA to YUV420P
        ffmpeg.sws_scale(sws, inData, lineSize, 0, codecContext->width, inputFrame->extended_data, inputFrame->linesize);
    }

    inputFrame->pts = frameCounter++;

    if(ffmpeg.avcodec_send_frame(codecContext, inputFrame) < 0)
        throw new ApplicationException("Error sending a frame for encoding!");

    pkt = new AVPacket();
    fixed(AVPacket* packet = &pkt)
        ffmpeg.av_init_packet(packet);
    pkt.data = null;
    pkt.size = 0;

    pinned.Free();
    ...
}


  



  sws_scale takes a sbyte** as the second parameter, therefore I'm trying to convert the input byte array to sbyte** by first pinning it with GCHandle and doing an explicit type conversion afterwards. I don't know if that's the correct way, though.

  



  Moreover, the condition if(ffmpeg.avcodec_send_frame(codecContext, inputFrame) < 0) alwasy throws an ApplicationException, where I also really don't know why this happens. codecContext and inputFrame are my AVCodecContext and AVFrame objects, respectively, and the fields are defined as the following :

  



  codecContext

  



  codecContext = ffmpeg.avcodec_alloc_context3(codec);
codecContext->bit_rate = 400000;
codecContext->width = textureWidth;
codecContext->height = textureHeight;

AVRational timeBase = new AVRational();
timeBase.num = 1;
timeBase.den = (int)fps;
codecContext->time_base = timeBase;
videoAVStream->time_base = timeBase;

AVRational frameRate = new AVRational();
frameRate.num = (int)fps;
frameRate.den = 1;
codecContext->framerate = frameRate;

codecContext->gop_size = 10;
codecContext->max_b_frames = 1;
codecContext->pix_fmt = AVPixelFormat.AV_PIX_FMT_YUV420P;


  



  inputFrame

  



  inputFrame = ffmpeg.av_frame_alloc();
inputFrame->format = (int)codecContext->pix_fmt;
inputFrame->width = textureWidth;
inputFrame->height = textureHeight;
inputFrame->linesize[0] = inputFrame->width;


  



  Any help in fixing the issue would be greatly appreciated :)