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• Feeding raw image bytes into ffmpeg rawvideo fails with Invalid buffer size on linux only

  13 février 2021, par cherouvim

  I have a nodejs program which generates raw (rgb24) image(s), which I then pipe into ffmpeg so it saves as png or mp4. My code looks like this :

  


  const fs = require("fs");
// ...
const outputBuffer = Buffer.alloc(outputPngWidth * 3 * outputPngHeight);
// ... write data into outputBuffer
fs.writeSync(process.stdout.fd, outputBuffer);


  


  I then do the following in CLI :

  


  node generate | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 1000x1000 -i - test.png


  


  Alternatively, if I generate lots of images from my program, I do this to generate the video file :

  


  node generate | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 1000x1000 -r 60 -i - -codec:v libx265 test.mp4


  


  On windows this works flawlessly. On linux (either on Ubuntu 20 VM, or Ubuntu 20 installed directly on a physical machine), it consistently fails with :

  


  pipe:: corrupt input packet in stream 0
[rawvideo @ 0x55f5256c8040] Invalid buffer size, packet size 65536 < expected frame_size 3000000
Error while decoding stream #0:0: Invalid argument


  


  If I split this in 2 phases like so, then it works perfectly on linux as well :

  


  node generate > test.raw
cat test.raw | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 1000x1000 -i - test.png


  


  By looking at the error "packet size 65536 < expected frame_size 3000000" it seems that node's fs.writeSync only sends 65536 bytes at a time, but ffmpeg expects 3000000 bytes (that is 1000 width * 1000 height * 3 channels).

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  If I reduce my image size to something small, e.g 50x50 or 100x100, then it works. As soon as x * y * 3 exceeds 65536, it fails (eg. 160x160 fails with "packet size 65536 < expected frame_size 76800" because 160 * 160 * 3 = 76800).

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  What I've tried so far to solve the issue without luck :

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  • Force node to spit out the whole buffer at once :

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  fs.writeSync(process.stdout.fd, outputBuffer, 0, outputBuffer.length);


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  • All suggestions of Add a big buffer to a pipe between two commands with various linux commands to buffer between node and ffmpeg.

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  • Use Ubuntu 18 instead of 20.

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  • Use node 12 instead of 15.

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  • Figure out a way to change the chunk size in https://nodejs.org/api/fs.html

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  Is there a way to overcome this ?

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• How to create a queue system with a discord.py bot

  20 août 2024, par Zamv

  I'm trying to create a bot with discord.py.

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  Also, I'm a beginner, so I'll be interested in what I can improve and any errors there are.

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  I've been stuck on trying to create this queue system for songs, the bot was working perfectly fine and played some urls before I implemented the play_next function. Now it doesn't even play the first song, even if it sends confirmation messages both in the terminal that in the discord channel. I know that the code might be a little confusing.

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  I wrote two main functions : "play_next" to play the next song in the queue and "play", the main command. Here is my play_next function :

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  async def play_next(self,ctx):
        if not ctx.voice_client.is_playing: #(don't know if this is correct as I also check if the bot isn't                     playing anything in the play function)
            
            if self.song.queue: 
                next_song = self.song_queue.pop(0) #deleting the first element of the queue, so if we have (song_0, song_1 and song_2) the bot should delete (song_0) making in fact song_1 the "next" song_0
                try:
                    ctx.voice_client.play(discord.FFmpegPCMAudio(next_song), 
                                          after=lambda e: self.bot.loop.create_task(self.play_next(ctx))) #Not gonna lie here, i asked chat gpt for this line, it should make the bot automatically play the next song one after another, correct me if I am wrong

#this is not important
                    embed = discord.Embed(
                        title="Song",
                        description=f"Now playing {next_song}",
                        color = 0x1DB954
                    )
                    await ctx.send(embed=embed)
                except Exception as e:
                    print(f"Error playing the next song: {e}")

            else:
                await ctx.voice_client.disconnect()  # disconnecting from the voice channel if the queue is empty
                print("Disconnected from the voice channel as the queue is empty.")


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  I think that the main problem of my bot is the play_next function, but here it is my "play" function :

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      @commands.command(pass_context=True)
    async def play(self, ctx, url: str):  
        if ctx.author.voice:  # first checking if the user is in a voice channel
            if not ctx.voice_client: #then checking if the bot is already connected to a voice channel
                channel = ctx.message.author.voice.channel 
                try:
                    await channel.connect()  #then joining
                    print("I joined the voice channel!")
                except Exception as e:
                    print(f"Failed to connect to the voice channel: {e}")
                    return

            song_path = f"song_{self.song_index}.mp3" #note, im using cogs, i declared self.song_index with the value of 0 
            self.song_index += 1 #i thought that this was the easiest way of creating a new file for each song

            ydl_opts = {
                'format': 'bestaudio/best',
                'postprocesors': [{
                    'key': 'FFmpegExtractAudio',
                    'preferredcodec': 'mp3',
                    'preferredquality': '192',
                }],
                'outtmpl': song_path
            }
            try:
                with youtube_dl.YoutubeDL(ydl_opts) as ydl:
                    print("Starting download...")
                    ydl.download([url]) #this is where it should download the song provided by the url
                    print("Download finished.")
            except Exception as e:
                await ctx.send(f"Failed to download the song: {e}")
                return

#i think that the next two if statements are the main threats
            if os.path.exists(song_path): #if there is atleast 1 song in the queue
                self.song_queue.append(song_path) #append the next one
                embed = discord.Embed(
                    title="Added to Queue!",
                    description = f"{url} has been added to the queue.",
                    color=0x33ff33
                )
                await ctx.send(embed=embed)


                if not ctx.voice_client.is_playing(): #checking if the bot is already playing something, don't know if i should put this if statement here
                    print("Starting playback...")
                    await self.play_next(ctx) #if nothing is playing, then the bot should play the next song



            else:
                await ctx.send("Failed to download or find the audio file.")

        else:
            embed = discord.Embed(
                title="❌You must be in a voice channel",
                color=0xff6666
            )
            await ctx.send(embed=embed)


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• Why doesn't the ffmpeg output display the stream in the browser ? [closed]

  10 mai 2024, par Tebyy

  Why is it that when I create a livestream in Python using ffmpeg, and then I open the browser and visit the page, the page keeps loading continuously, and in PyCharm logs, I see binary data ? There are no errors displayed, and the code seems correct to me. I even tried saving to a file for testing purposes, and when I play the video, everything works fine. Does anyone know what might be wrong here ?

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  Code :

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  def generate_frames():
    cap = cv2.VideoCapture(os.path.normpath(app_root_dir().joinpath("data/temp", "video-979257305707693982.mp4")))
    while cap.isOpened():
        ret, frame = cap.read()
        if not ret:
            break

        yield frame


@app.route('/video_feed')
def video_feed():
    ffmpeg_command = [
        'ffmpeg', '-f', 'rawvideo', '-pix_fmt', 'bgr24',
        '-s:v', '1920x1080', '-r', '60',
        '-i', '-', '-vf', 'setpts=2.5*PTS', # Video Speed
        '-c:v', 'libvpx-vp9', '-g', '60', '-keyint_min', '60',
        '-b:v', '6M', '-minrate', '4M', '-maxrate', '12M', '-bufsize', '8M',
        '-crf', '0', '-deadline', 'realtime', '-tune', 'psnr', '-quality', 'good',
        '-tile-columns', '6', '-threads', '8', '-lag-in-frames', '16',
        '-f', 'webm', '-'
    ]
    ffmpeg_process = subprocess.Popen(ffmpeg_command, stdin=subprocess.PIPE, stderr=subprocess.PIPE, bufsize=-1)
    frames_generator = generate_frames()
    for frame in frames_generator:
        ffmpeg_process.stdin.write(frame)
        ffmpeg_process.stdin.flush()

    ffmpeg_process.stdin.close()
    ffmpeg_process.wait()

    def generate_video_stream(process):
        startTime = time.time()
        buffer = []
        sentBurst = False
        for chunk in iter(lambda: process.stderr.read(4096), b''):
            buffer.append(chunk)

            # Minimum buffer time, 3 seconds
            if sentBurst is False and time.time() > startTime + 3 and len(buffer) > 0:
                sentBurst = True
                for i in range(0, len(buffer) - 2):
                    print("Send initial burst #", i)
                    yield buffer.pop(0)

            elif time.time() > startTime + 3 and len(buffer) > 0:
                yield buffer.pop(0)

            process.poll()
            if isinstance(process.returncode, int):
                if process.returncode > 0:
                    print('FFmpeg Error', process.returncode)

                break

    return Response(stream_with_context(generate_video_stream(ffmpeg_process)), mimetype='video/webm', content_type="video/webm; codecs=vp9", headers=Headers([("Connection", "close")]))



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