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• Seeking with ffmpeg options fails or causes delayed playback in Discord bot

  29 août 2022, par J Petersen

  My Discord bot allows users to play a song starting from a timestamp.

  


  The problem is that playback is delayed and audio plays faster and is jumbled if start times >= 30s are set.

  


  Results from testing different start times. Same URL, 30 second duration :

  


  





  


  


  


  


  


  



  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  Entered Start Time (s)	Playback Delay (s)	Song Playback Time (s)
  0	3	30
  30	10	22
  60	17	17
  120	31	2
  150	120	<1

  


  


  I am setting the start time using ffmpeg_options as suggested in this question.

  


  Does anyone understand why the audio playback is being delayed/jumbled ? How can I improve playback delay and allow users to start in the middle of a multi-chapter YouTube video ?

  


  Code :

  


  import discord
import youtube_dl
import asyncio


# Suppress noise about console usage from errors
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": False,
    "yesplaylist": 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 at certain times
}

ytdl = youtube_dl.YoutubeDL(ytdl_format_options)


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

        self.data = data

        self.title = data.get("title")
        self.url = data.get("url")

    @classmethod
    async def from_url(cls, url, *, loop=None, stream=False, timestamp = 0):
        ffmpeg_options = {
            "options": f"-vn -ss {timestamp}"}

        loop = loop or asyncio.get_event_loop()

        data = await loop.run_in_executor(None, lambda: ytdl.extract_info(url, download=not stream))
        if "entries" in data:
            # Takes the first item from a playlist
            data = data["entries"][0]

        filename = data["url"] if stream else ytdl.prepare_filename(data)
        return cls(discord.FFmpegPCMAudio(filename, **ffmpeg_options), data=data)


intents = discord.Intents.default()

bot = discord.Bot(intents=intents)

@bot.slash_command()
async def play(ctx, audio: discord.Option(), seconds: discord.Option(), timestamp: discord.Option()):
    channel = ctx.author.voice.channel
    voice = await channel.connect()
    player = await YTDLSource.from_url(audio, loop=bot.loop, stream=True, timestamp=int(timestamp))
    voice.play(player)
    await asyncio.sleep(int(seconds))
    await voice.disconnect()

token = token value
bot.run(token)


  


• How to see default NVENC hevc options in ffmpeg

  18 mars 2023, par Ivan Gorin

  I am trying to use the hevc_nvenc encoder in ffmpeg to reencode an old video I have. Obviously software encoding using libx265 would be better, but I want to make in fast. I am trying to optimize for video quality, so I am using these options :

  


  -profile:v main -b_ref_mode 0 -preset p7 -tune hq -rc vbr


  


  b_ref_mode 0 since my gpu doesn't support bframe reference mode.

  


  This gives results with average bitrate of around 2M, so I am guessing that is the default bitrate setting for nvenc. Increasing -b:v increases average bitrate, but around 6.5M it stops. Even using -b:v 50M gives the same video bitrate. I have also tried setting -cq 1 to force the best quality possible, but that actually decreases bitrate to around 4.5M. The only way I found to get the desired bitrate is using -cq 1 and -maxrate set to a big value. This removes the restriction, and actually the -b:v option is no longer needed, it seems like it doesn't have any effect at all.

  


  All of this behaviour seems very strange to me, with some hidden default values for bitrate and maxrate, so the question is where can I see these values ? I tried using ffmpeg with -loglevel debug but didn't see these values getting passed, and the documentation I found says maxrate default in ffmpeg is 0 (what does this mean ?).

  


• Sending Blobs from a Chrome Extension to a Node.js Process without WebSockets [closed]

  29 octobre 2023, par Matrix 404

  Question :
I have a Puppeteer script that runs a Chrome extension, which opens a webpage. The extension records that tab and sends the recorded blobs to the main Node.js process using WebSockets. The main process then streams these blobs to an RTMP server.

  


  I'm looking for an alternative method to send blobs to the main process without using WebSockets. Additionally, I want to know if it's possible to stream these blobs directly from the browser using FFmpeg wasm.

  


  Details :

  


  


  1. My current setup : Puppeteer script -> Chrome extension (recording) -> WebSockets -> Node.js process -> RTMP server.

     


  


  2. I'm exploring options to eliminate the use of WebSockets while maintaining the ability to send recorded blobs from the Chrome extension to the Node.js process efficiently.

     


  


  3. Is it possible to use FFmpeg wasm to stream blobs directly from the browser to an RTMP server ? If so, how can this be achieved ?

     


  


  


  Additional Information :

  


  

  • The technology stack I'm using includes Puppeteer, Chrome extension, Node.js, and FFmpeg.

  


  • Any code snippets, examples, or recommended libraries are greatly appreciated.

  


  


  Constraints :

  


  

  • Compatibility with modern browsers and reasonable performance are essential.

  


  • Ideally, the solution should work in a headless Chrome instance.

  


  


  Thank you for your assistance in finding an efficient solution to this problem !

  


  

  • The technology stack I'm using includes Puppeteer, Chrome extension, Node.js, and FFmpeg.

  


  • Any code snippets, examples, or recommended libraries are greatly appreciated.