Filter SDK/avs2pcm

Revision as of 23:36, 21 February 2014

avs2pcm reads a script and outputs raw audio.

Here's avs2pcm.cpp:

#include <stdio.h>
#include <Windows.h>
#include "avisynth.h"

#define MY_VERSION "Avs2PCM 0.01"

const AVS_Linkage *AVS_linkage = 0;

int __cdecl main(int argc, const char* argv[])
{
  const char* infile = NULL;
  const char* outfile = NULL;
  FILE* out_fh;

  if (!strcmp(argv[1], "-h")) {
    fprintf(stderr, MY_VERSION "\n"
    "Usage: avs2pcm in.avs out.pcm\n");
    return 2;
  } else {
    infile = argv[1];
    outfile = argv[2];
  }

  try {
    char* sample_type;
    typedef IScriptEnvironment* (__stdcall *DLLFUNC)(int);
    IScriptEnvironment* env;
    HMODULE avsdll = LoadLibrary("avisynth.dll");
    if (!avsdll) {
      fprintf(stderr, "failed to load avisynth.dll\n");
      return 2;
    }

    DLLFUNC CreateEnv = (DLLFUNC)GetProcAddress(avsdll, "CreateScriptEnvironment");
    if (!CreateEnv) {
      fprintf(stderr, "failed to load CreateScriptEnvironment()\n");
      FreeLibrary(avsdll);
      return 1;
    }

    env = CreateEnv(AVISYNTH_INTERFACE_VERSION);
    AVS_linkage = env->GetAVSLinkage();
    AVSValue arg(infile);
    AVSValue res = env->Invoke("Import", AVSValue(&arg, 1));
    if (!res.IsClip()) {
      fprintf(stderr, "Error: '%s' didn't return a video clip.\n", infile);
      FreeLibrary(avsdll);
      return 1;
    }

    PClip clip = res.AsClip();

    if (clip->GetVersion() < 5) {
      fprintf(stderr, "Error: too old version ('%d') of avisynth.dll loaded.\nplease install v2.60 or later.\n",
              clip->GetVersion());
      return 1;
    }

    VideoInfo vi = clip->GetVideoInfo();

    if (!vi.HasAudio()) {
      fprintf(stderr, "Error: '%s' video only clip.\n", infile);
      FreeLibrary(avsdll);
      return 1;
    }

    fprintf(stderr, " %s:\n", infile);
    fprintf(stderr, " %d Herz,\n", vi.audio_samples_per_second);
    fprintf(stderr, " %d channels,\n", vi.nchannels);
    fprintf(stderr, " %I64d audio samples,\n", vi.num_audio_samples);

    switch(vi.SampleType()) {
    case SAMPLE_INT8 : sample_type = "8 bit";
      break;
    case SAMPLE_INT16 : sample_type = "16 bit";
      break;
    case SAMPLE_INT24 : sample_type = "24 bit";
      break;
    case SAMPLE_INT32 :
    case SAMPLE_FLOAT : sample_type = "32 bit";
      break;
    default: sample_type = "unknown sample type";
      break;
    }

    fprintf(stderr, " %s", sample_type);

    out_fh = fopen(outfile, "wb");
    if (!out_fh) {
      fprintf(stderr, "fopen(\"%s\") failed", outfile);
      FreeLibrary(avsdll);
      return 1;
    }

    const __int64 start = 0;
    const __int64 count = vi.num_audio_samples;
    const int channels = vi.AudioChannels();
    __int64 bytes = vi.BytesFromAudioSamples(count);
    int BlockAlign = vi.AudioChannels() * vi.BytesPerAudioSample();

    unsigned char* samples = new unsigned char[BlockAlign*count];
    clip->GetAudio(samples, start, count, env);
    fwrite(samples, bytes, 1, out_fh);

    delete[] samples;
    env->DeleteScriptEnvironment();
    FreeLibrary(avsdll);
    AVS_linkage = 0;

    } catch(AvisynthError err) {
      fprintf(stderr, "\nAvisynth error:\n%s\n", err.msg);
      return 1;
    }

    fclose(out_fh);
    return 0;
}

Compile this file into an EXE named avs2pcm.exe. See compiling instructions. Now open the command line and go to the folder where avs2pcm.exe and your script (called example.avs here) are located. Our script:

Tone(length=1, frequency=2, samplerate=48000, channels=1, type="square", level=1.0) # float
ConvertAudioTo16Bit()

Type the following on the command line (the name of the output clip can be arbitrary in our application):

avs2pcm.exe example.avs output.pcm

So the output file will contain five frames of YV12 data (640x480). You can import it in AviSynth using the plugin NicAudio:

v = Blankclip(1000)
a = RaWavSource("D:\AviSynth\Plugins\avs2pcm\test_16bit.pcm", 48000, 16, 1) # little-endian
Audiodub(v,a).ConvertAudioTo16Bit().GetChannels(1)
Audiograph(20) # Audiograph doesn't support 24/32bit nor multichannel

Line by line breakdown

Here's a line-by-line breakdown of avs2pcm.cpp:

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