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• How can I play a video from the CLI with no output of video or audio

  1er janvier 2023, par Gary

  I have 1000s of video files and I know some of them are corrupted. I want to be able to detect corrupted files with a bash script, I tried using FFmpeg with error logging :

  


  ffmpeg -v error -i "vid.avi" -f null - 2>"vid.log"


  


  The output doesn't seem to be very useful though, some files which report errors play without any problems. The only way to know for sure seems to be to watch the video to see if there is any corruption or if it crashes the media player.

  


  I would like to be able to automate the "watching" by playing the video from the command line and detecting the corruption or crashing there but I can't find a way to run it without outputting the video and audio.

  


  I have tried FFplay but I can only disable one of the outputs not both :

  


  ffplay -nodisp "vid.avi"
ffplay -vn "vid.avi"


  


  These disable the video :

  


  ffplay -an "vid.avi"


  


  This disables the audio but I can't combine them, when I do I get an error :

  


  Failed to open file 'vid.avi' or configure filtergraph


  


  I have tried using the vlc/cvlv suggestions I have found but none have worked, it still opens a graphical interface just with no controls.

  


  Is there any way to do this ?

  


• discord.py music bot slowing down for longer audio queries

  1er janvier 2023, par Bobluge

  So I'm trying to make a music bot with discord.py. Shown below is a minimum working example of the bot with the problematic functions :

  


  import os

import discord
from discord.ext import commands
from discord import player as p

import yt_dlp as youtube_dl

intents = discord.Intents.default()
intents.members = True

bot = commands.Bot(command_prefix=';')

class Music(commands.Cog):
    def __init__(self, bot):
        self.bot = bot
        self.yt-dlp_opts = {
            'format': 'bestaudio/best',
            'outtmpl': '%(extractor)s-%(id)s-%(title)s.%(ext)s',
            'restrictfilenames': True,
            'noplaylist': True,
            'playlistend': 1,
            '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
        }
        self.ffmpeg_opts = {
            'options': '-vn',
            # Source: https://stackoverflow.com/questions/66070749/
            "before_options": "-reconnect 1 -reconnect_streamed 1 -reconnect_delay_max 5",
        }
        self.cur_stream = None
        self.cur_link = None

    @commands.command(aliases=["p"])
    async def play(self, ctx, url):
        yt-dlp = youtube_dl.YoutubeDL(self.ytdl_opts)
        data = yt-dlp.extract_info(url, download=False)
        filename = data['url']  # So far only works with links
        print(filename)
        audio = p.FFmpegPCMAudio(filename, **self.ffmpeg_opts)
        self.cur_stream = audio
        self.cur_link = filename

        # You must be connected to a voice channel first
        await ctx.author.voice.channel.connect()
        ctx.voice_client.play(audio)
        await ctx.send(f"now playing")

    @commands.command(aliases=["ff"])
    async def seek(self, ctx):
        """
        Fast forwards 10 seconds
        """
        ctx.voice_client.pause()
        for _ in range(500):
            self.cur_stream.read()  # 500*20ms of audio = 10000ms = 10s
        ctx.voice_client.resume()

        await ctx.send(f"fast forwarded 10 seconds")

    @commands.command(aliases=["j"])
    async def jump(self, ctx, time):
        """
        Jumps to a time in the song, input in the format of HH:MM:SS
        """
        ctx.voice_client.stop()
        temp_ffempg = {
            'options': '-vn',
            # Keyframe skipping when passed as an input option (fast)
            "before_options": f"-ss {time} -reconnect 1 -reconnect_streamed 1 -reconnect_delay_max 5",
        }
        new_audio = p.FFmpegPCMAudio(self.cur_link, **temp_ffempg)
        self.cur_stream = new_audio
        ctx.voice_client.play(new_audio)
        await ctx.send(f"skipped to {time}")


bot.add_cog(Music(bot))
bot.run(os.environ["BOT_TOKEN"])


  


  My requirements.txt file :

  


  discord.py[voice]==1.7.3
yt-dlp==2021.9.2


  


  To play a song in Discord the following format is used :

  


  ;p 


  


  Where is any link that yt-dlp supports. Under normal circumstances, the ;p command is used with songs that are relatively short, to which seek() and jump() work extremely quickly to do what they are supposed to do. For example if I execute these sequence of commands in Discord :

  


  ;p https://www.youtube.com/watch?v=n8X9_MgEdCg  <- 4 min song


  


  And when the bot starts playing, spam the following :

  


  ;ff
;ff
;ff
;ff
;ff


  


  The bot is able to almost instantly seek five 10-second increments of the song. Additionally, I can jump to the three minute mark very quickly with :

  


  ;j 00:03:00


  


  From some experimentation, the seek() and jump() functions seem to work quickly for songs that are under 10 minutes. If I try the exact same sequence of commands but with a 15 minute song like https://www.youtube.com/watch?v=Ks9Ck5LfGWE or longer https://www.youtube.com/watch?v=VThrx5MRJXA (10 hours classical music), there is an evident slowdown when running the ;ff command. However, when I include a few seconds of delay between firings of the ;ff command, the seeking is just as fast as previously mentioned. I'm not exactly sure what is going on with yt-dlp/FFmpeg behind the scenes when streaming, but I speculate that there is some sort of internal buffer, and songs that pass a certain length threshold are processed differently.

  


  For longer songs, the seek() command takes longer to get to the desired position, which makes sense since this site specifies that -ss used as an input option loops through keyframes (as there must be more keyframes in longer songs). However, if the following commands are run in Discord :

  


  ;p https://www.youtube.com/watch?v=VThrx5MRJXA  <- 10 hour classical music
;j 09:00:00                                     <- jump to 9 hour mark
;j 00:03:00                                     <- jump to 3 minute mark


  


  The first seek command takes around 5 to 10 seconds to perform a successful seek, which isn't bad, but it could be better. The second seek command takes around the same time as the first command, which doesn't make sense to me, because I thought less keyframes were skipped in order to reach the 3 minute mark.

  


  So I'm wondering what's going on, and how to potentially solve the following :

  


  

  • What is actually going on with the seek() command ? My implementation of seek() uses discord.py's discord.player.FFmpegPCMAudio.read() method, which apparently runs slower if the song's length is longer ? Why ?

  


  • Why does input seeking for long YouTube videos take almost the same time no matter where I seek to ?

  


  • How the yt-dlp and FFmpeg commands work behind the scenes to stream a video from YouTube (or any other website that YTDL supports). Does yt-dlp and FFmpeg behave differently for audio streams above a certain length threshold ?

  


  • Potential ways to speed up seek() and jump() for long songs. I recall some well-known discord music bots were able to do this very quickly.

  


  


• How do I record a Selenium Grid Session (Via VNC, Remote Frame Buffer - RFB) to an H264 encoded MP4 [closed]

  25 février, par Frobbit

  When my integration tests fail, I want to be able to watch the video of the test running. I test a full stack app with docker-compose and I use the single container Selenium-grid. If I save every Secenerio to a file, I can quickly review a failed test.

  


  I'm trying to record a Selenium Grid session and save it as an MP4 file using GStreamer and VNC. I need a solution that captures the VNC session running in the Selenium Grid container and writes the output to an H264 encoded mp4 file.

  


  Here's the context :

  


  I'm using Selenium Grid with a VNC server running in the container.
I can access the VNC session using the se:vncLocalAddress capability.

  


  I would like a tool that can record the VNC remote framebuffer (RFB) output.

  


  Can someone provide a reliable way to record a Selenium Grid session to an MP4 file using a tool like GStreamer or ffmpeg ?