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• ffmpeg - how can I get a specific channel using channel masks (e.g. : get only surround left channel)

  26 novembre 2013, par awfulcode

  I'm trying to build a mixer that allows users to toggle specific channels on and off. I know that different codecs encode those channels in different orders (it's not as simple as getting channel #3 as the center channel every time), so the challenge is to properly identify the channel position in surround audio tracks.

  ffmpeg does list the in the beginning of libavutil/channel_layout.h :

  #define AV_CH_FRONT_LEFT             0x00000001
  
  #define AV_CH_FRONT_RIGHT            0x00000002
  
  #define AV_CH_FRONT_CENTER           0x00000004
  
  #define AV_CH_LOW_FREQUENCY          0x00000008
  
  #define AV_CH_BACK_LEFT              0x00000010
  
  #define AV_CH_BACK_RIGHT             0x00000020
  
  #define AV_CH_FRONT_LEFT_OF_CENTER   0x00000040
  
  #define AV_CH_FRONT_RIGHT_OF_CENTER  0x00000080
  
  #define AV_CH_BACK_CENTER            0x00000100
  
  #define AV_CH_SIDE_LEFT              0x00000200
  
  #define AV_CH_SIDE_RIGHT             0x00000400
  
  #define AV_CH_TOP_CENTER             0x00000800
  
  #define AV_CH_TOP_FRONT_LEFT         0x00001000
  
  #define AV_CH_TOP_FRONT_CENTER       0x00002000
  
  #define AV_CH_TOP_FRONT_RIGHT        0x00004000
  
  #define AV_CH_TOP_BACK_LEFT          0x00008000
  
  #define AV_CH_TOP_BACK_CENTER        0x00010000
  
  #define AV_CH_TOP_BACK_RIGHT         0x00020000
  
  #define AV_CH_STEREO_LEFT            0x20000000  ///< Stereo downmix.
  
  #define AV_CH_STEREO_RIGHT           0x40000000  ///< See AV_CH_STEREO_LEFT.
  
  #define AV_CH_WIDE_LEFT              0x0000000080000000ULL
  
  #define AV_CH_WIDE_RIGHT             0x0000000100000000ULL
  
  #define AV_CH_SURROUND_DIRECT_LEFT   0x0000000200000000ULL
  
  #define AV_CH_SURROUND_DIRECT_RIGHT  0x0000000400000000ULL
  
  #define AV_CH_LOW_FREQUENCY_2        0x0000000800000000ULL

  But looking over the header files and whatever little documentation about ffmpeg I couldn't find anything that tells me how to assign a specific channel position (or mask, as it's described in the header file) to a specific bus in a mixer audio unit.

  Do you know how to do that ? Please let me know if you want to look at the code I'm using right now.

  And as always, thank you so much.

• Youtube Dlp returns with error code of 400 [closed]

  10 mars 2024, par nikita goncharov

  I have a python discord bot that can play music and uses discord.py https://discordpy.readthedocs.io/en/stable/. To play get the music I use yt_dlp or youtube_dl. But when requesting a video it returns with a 400 error code.

  


  This is the error with yt_dlp :

  


  WARNING: [youtube] YouTube said: ERROR - Precondition check failed.

  


  WARNING: [youtube] HTTP Error 400: Bad Request. Retrying (1/3)...

  


  WARNING: [youtube] YouTube said: ERROR - Precondition check failed.

  


  WARNING: [youtube] HTTP Error 400: Bad Request. Retrying (2/3)...

  


  WARNING: [youtube] YouTube said: ERROR - Precondition check failed.

  


  WARNING: [youtube] HTTP Error 400: Bad Request. Retrying (3/3)...

  


  WARNING: [youtube] YouTube said: ERROR - Precondition check failed.

  


  WARNING: [youtube] Unable to download API page: HTTP Error 400: Bad Request (caused by <httperror>)</httperror>

  


  I will leave some of the code that I use for my bot... The youtube setup settings :

  


  import youtube_dl

  


  or

  


  import yt_dlp as youtube_dl

  


  youtube_dl.utils.bug_reports_message = lambda: ''


ytdl_format_options = {
    'format': 'bestaudio/best',
    'outtmpl': '%(extractor)s-%(id)s-%(title)s.%(ext)s',
    'restrictfilenames': True,
    'noplaylist': True,
    'nocheckcertificate': True,
    'ignoreerrors': False,
    'logtostderr': False,
    'quiet': True,
    'no_warnings': True,
    'default_search': 'auto',
    'source_address': '0.0.0.0',  # bind to ipv4 since ipv6 addresses cause issues sometimes
}

ffmpeg_options = {
    'options': '-vn',
}

ytdl = youtube_dl.YoutubeDL(ytdl_format_options)


class YTDLSource(discord.PCMVolumeTransformer):
    def __init__(self, source, *, data, volume=0.5):
        super().__init__(source, volume)

        self.data = data

        self.title = data.get('title')
        self.url = data.get('url')
        self.duration = data.get('duration')
        self.image = data.get("thumbnails")[0]["url"]
    @classmethod
    async def from_url(cls, url, *, loop=None, stream=False):
        loop = loop or asyncio.get_event_loop()
        data = await loop.run_in_executor(None, lambda: ytdl.extract_info(url, download=not stream))
        #print(data)

        if 'entries' in data:
            # take first item from a playlist
            data = data['entries'][0]
        #print(data["thumbnails"][0]["url"])
        #print(data["duration"])
        filename = data['url'] if stream else ytdl.prepare_filename(data)
        return cls(discord.FFmpegPCMAudio(filename, **ffmpeg_options), data=data)


  


  Approximately the command to run the audio (from my bot) :

  


  sessionChanel = message.author.voice.channel await sessionChannel.connect() url = matched.group(1) player = await YTDLSource.from_url(url, loop=client.loop, stream=True) sessionChannel.guild.voice_client.play(player, after=lambda e: print(                                        f'Player error: {e}') if e else None) 


  


  I searched for posts with the same error and they where either old or didn't solve my problem.

  


  I tried importing instead of yt_dlp, I tried importing youtube_dl. But when I make the request it does not answer, no exception and no warning it just does not answer, as if the funcion is empty

  


  I will link my other post that I asked. It might be usefull : Error : Unable to extract uploader id - Youtube, Discord.py

  


• Revision 97268 : Ne pas se tromper sur le nombre d’erreurs dans le joli message.

  7 mai 2016, par marcimat@… — Log

  Ne pas se tromper sur le nombre d’erreurs dans le joli message.