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• FFMPEG : Create output depending on the input's streams

  14 novembre 2022, par Javierd98

  I'm working on a project where I need to use FFMPEG CLI to generate a video and an audio file from a single input. This is a pretty simple command like :

  


  ffmpeg -i input.mp4 -y -map 0:a:0? -acodec mp2 -f mp2 audio.mp2 -map 0:v:0? -f mp4 -vcodec libx264 video.mp4


  


  So, the main problem I'm experiencing is that I don't really know whether the input has audio/video, it could be a mp4 file with no video or audio streams. In those cases, FFMPEG fails as there is no stream to associate to one of the outputs.

  


  Is there any way I could tell FFMPEG to only create the output if the corresponding input stream exists ? If not, I found this question showing how to add blank audio if there's no input audio, how could I create an empty video too ? Is there any other possible solution ?

  


  Thanks a lot for your help.

  


• Use C# to converting apng to webm with ffmpeg from pipe input and output

  30 novembre 2022, par martin wang

  I was using ffmpeg to convert Line sticker from apng file to webm file.
And the result is weird, some of them was converted successed and some of them failed.
not sure what happend with these failed convert.

  


  Here is my c# code to convert Line sticker to webm,
and I use CliWrap to run ffmpeg command line.

  


  async Task Main()
{

    var downloadUrl = @"http://dl.stickershop.LINE.naver.jp/products/0/0/1/23303/iphone/stickerpack@2x.zip";
    var arg = @$"-i pipe:.png -vf scale=512:512:force_original_aspect_ratio=decrease:flags=lanczos -pix_fmt yuva420p -c:v libvpx-vp9 -cpu-used 5 -minrate 50k -b:v 350k -maxrate 450k -to 00:00:02.900 -an -y -f webm pipe:1";

    var errorCount = 0;
    try
    {
        using (var hc = new HttpClient())
        {
            var imgsZip = await hc.GetStreamAsync(downloadUrl);

            using (ZipArchive zipFile = new ZipArchive(imgsZip))
            {
                var files = zipFile.Entries.Where(entry => Regex.IsMatch(entry.FullName, @"animation@2x\/\d+\@2x.png"));
                foreach (var entry in files)
                {
                    try
                    {
                        using (var fileStream = File.Create(Path.Combine("D:", "Projects", "ffmpeg", "Temp", $"{Path.GetFileNameWithoutExtension(entry.Name)}.webm")))
                        using (var pngFileStream = File.Create(Path.Combine("D:", "Projects", "ffmpeg", "Temp", $"{entry.Name}")))
                        using (var entryStream = entry.Open())
                        using (MemoryStream ms = new MemoryStream())
                        {
                            entry.Open().CopyTo(pngFileStream);

                            var result = await Cli.Wrap("ffmpeg")
                                         .WithArguments(arg)
                                         .WithStandardInputPipe(PipeSource.FromStream(entryStream))
                                         .WithStandardOutputPipe(PipeTarget.ToStream(ms))
                                         .WithStandardErrorPipe(PipeTarget.ToFile(Path.Combine("D:", "Projects", "ffmpeg", "Temp", $"{Path.GetFileNameWithoutExtension(entry.Name)}Info.txt")))
                                         .WithValidation(CommandResultValidation.ZeroExitCode)
                                         .ExecuteAsync();
                            ms.Seek(0, SeekOrigin.Begin);
                            ms.WriteTo(fileStream);
                        }
                    }
                    catch (Exception ex)
                    {
                        entry.FullName.Dump();
                        ex.Dump();
                        errorCount++;
                    }
                }
            }

        }
    }
    catch (Exception ex)
    {
        ex.Dump();
    }
    $"Error Count:{errorCount.Dump()}".Dump();

}


  


  This is the failed convert file's error information from ffmpeg :

  


  

  


  And the successed convert file from ffmpeg infromation :


  


  It's strange when I was manually converted these failed convert file from command line, and it will be converted successed.


  


  The question is the resource of images are all the same apng file,
so I just can't understan why some of files will convert failed from my c# code
but also when I manually use command line will be converted successed ?

  


  ---

  


  I have written same exampe from C# to Python...
and here is python code :

  


  from io import BytesIO
import os
import re
import subprocess
import zipfile

import requests


downloadUrl = "http://dl.stickershop.LINE.naver.jp/products/0/0/1/23303/iphone/stickerpack@2x.zip"
args = [
    'ffmpeg',
    '-i', 'pipe:',
    '-vf', 'scale=512:512:force_original_aspect_ratio=decrease:flags=lanczos',
    '-pix_fmt', 'yuva420p',
    '-c:v', 'libvpx-vp9',
    '-cpu-used', '5',
    '-minrate', '50k',
    '-b:v', '350k',
    '-maxrate', '450k', '-to', '00:00:02.900', '-an', '-y', '-f', 'webm', 'pipe:1'
]


imgsZip = requests.get(downloadUrl)
with zipfile.ZipFile(BytesIO(imgsZip.content)) as archive:
    files = [file for file in archive.infolist() if re.match(
        "animation@2x\/\d+\@2x.png", file.filename)]
    for entry in files:
        fileName = entry.filename.replace(
            "animation@2x/", "").replace(".png", "")
        rootPath = 'D:\\' + os.path.join("Projects", "ffmpeg", "Temp")
        # original file
        apngFile = os.path.join(rootPath, fileName+'.png')
        # output file
        webmFile = os.path.join(rootPath, fileName+'.webm')
        # output info
        infoFile = os.path.join(rootPath, fileName+'info.txt')

        with archive.open(entry) as file, open(apngFile, 'wb') as output_apng, open(webmFile, 'wb') as output_webm, open(infoFile, 'wb') as output_info:
            p = subprocess.Popen(args, stdin=subprocess.PIPE,
                                 stdout=subprocess.PIPE, stderr=output_info)
            outputBytes = p.communicate(input=file.read())[0]

            output_webm.write(outputBytes)
            file.seek(0)
            output_apng.write(file.read())



  


  And you can try it,the result will be the as same as C#.

  


• How to list all audio devices that are enabled and present for recording the output audio of the pc ?

  23 juin 2023, par Daniel Lip

  I want to record with ffmpeg later the entire desktop including audio.
I want to make that it will find for me automatic the recording audio device.

  


  I'm using MMDeviceEnumerator.

  


  all the other ways I tried returned empty list returned 0 audio devices. I tried with naudio and ffmpeg

  


  public Form1()
        {
            InitializeComponent();

            InitializeRecordingIndicator();

            MMDeviceEnumerator enumerator = new MMDeviceEnumerator();
            foreach (MMDevice device in enumerator.EnumerateAudioEndPoints(DataFlow.Capture, DeviceState.All))
            {
                StreamWriter w = new StreamWriter(@"d:\audiodev.txt", true);
                cmbAudioDevices.Items.Add(device.FriendlyName);
                w.WriteLine(device.FriendlyName + " " + device.State);
                w.Close();
            }
        }


  


  This is the list of all my audio deviceso n my system.
but they are all not present or disabled. and i have audio on my pc i can hear games videos anything.

  


  so what would i select from this list as audio device for recording the pc output audio ?
or maybe i need to find another way to find the right audio device ?

  


  Front Green In (Realtek(R) Audio) NotPresent
Rear (Realtek(R) Audio) NotPresent
Center (Realtek(R) Audio) NotPresent
Microphone (Realtek(R) Audio) NotPresent
Rear Grey In (Realtek(R) Audio) NotPresent
Side (Realtek(R) Audio) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Rear Pink In (Realtek(R) Audio) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Front (Realtek(R) Audio) NotPresent
Rear Orange In (Realtek(R) Audio) NotPresent
Line In (Realtek(R) Audio) NotPresent
Front Pink In (Realtek(R) Audio) NotPresent
Line In (Realtek(R) Audio) Unplugged
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Microphone (Realtek(R) Audio) Unplugged
Subwoofer (Realtek(R) Audio) NotPresent
Rear Black In (Realtek(R) Audio) NotPresent
Stereo Mix (Realtek(R) Audio) Disabled
Rear Green In (Realtek(R) Audio) NotPresent
Microphone (Realtek(R) Audio) NotPresent
Rear Blue In (Realtek(R) Audio) NotPresent
Front Green In (Realtek(R) Audio) NotPresent
Rear (Realtek(R) Audio) NotPresent
Center (Realtek(R) Audio) NotPresent
Microphone (Realtek(R) Audio) NotPresent
Rear Grey In (Realtek(R) Audio) NotPresent
Side (Realtek(R) Audio) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Rear Pink In (Realtek(R) Audio) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Front (Realtek(R) Audio) NotPresent
Rear Orange In (Realtek(R) Audio) NotPresent
Line In (Realtek(R) Audio) NotPresent
Front Pink In (Realtek(R) Audio) NotPresent
Line In (Realtek(R) Audio) Unplugged
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Microphone (Realtek(R) Audio) Unplugged
Subwoofer (Realtek(R) Audio) NotPresent
Rear Black In (Realtek(R) Audio) NotPresent
Stereo Mix (Realtek(R) Audio) Disabled
Rear Green In (Realtek(R) Audio) NotPresent
Microphone (Realtek(R) Audio) NotPresent
Rear Blue In (Realtek(R) Audio) NotPresent
Front Green In (Realtek(R) Audio) NotPresent
Rear (Realtek(R) Audio) NotPresent
Center (Realtek(R) Audio) NotPresent
Microphone (Realtek(R) Audio) NotPresent
Rear Grey In (Realtek(R) Audio) NotPresent
Side (Realtek(R) Audio) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Rear Pink In (Realtek(R) Audio) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (NVIDIA High Definition Audio) NotPresent
Front (Realtek(R) Audio) NotPresent
Rear Orange In (Realtek(R) Audio) NotPresent
Line In (Realtek(R) Audio) NotPresent
Front Pink In (Realtek(R) Audio) NotPresent
Line In (Realtek(R) Audio) Unplugged
Internal AUX Jack (High Definition Audio Device) NotPresent
Internal AUX Jack (High Definition Audio Device) NotPresent
Microphone (Realtek(R) Audio) Unplugged
Subwoofer (Realtek(R) Audio) NotPresent
Rear Black In (Realtek(R) Audio) NotPresent
Stereo Mix (Realtek(R) Audio) Disabled
Rear Green In (Realtek(R) Audio) NotPresent
Microphone (Realtek(R) Audio) NotPresent
Rear Blue In (Realtek(R) Audio) NotPresent


  


  this is how i tried with naudio but it didn't working it didn't find anything. :

  


  using NAudio.Wave;
...

// Enumerate and list audio input devices
var devices = WaveInEvent.DeviceCount;
for (int deviceId = 0; deviceId < devices; deviceId++)
{
    var deviceInfo = WaveInEvent.GetCapabilities(deviceId);
    Console.WriteLine($"Device ID: {deviceId}, Name: {deviceInfo.ProductName}");
}


  


  before that i tried with ffmpeg but also it didn't return anything :

  


  public static class FFmpegHelper
    {
        public static string[] GetAudioCaptureDevices()
        {
            string ffmpegPath = @"C:\path\to\ffmpeg.exe";
            Process process = new Process();
            process.StartInfo.FileName = ffmpegPath;
            process.StartInfo.Arguments = "-list_devices true -f dshow -i dummy";
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.RedirectStandardError = true;
            process.StartInfo.CreateNoWindow = true;
            process.Start();
            process.WaitForExit();

            string output = process.StandardError.ReadToEnd();
            string[] lines = output.Split('\n');
            var devices = lines.Where(line => line.Contains("audio")).Select(line => line.Trim()).ToArray();
            return devices;
        }
    }


  


  using it :

  


  var audioDevices = FFmpegHelper.GetAudioCaptureDevices();