Re: [LAD] Replaygain for video?

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To: <linux-audio-dev@...>
Date: Saturday, December 10, 2011 - 10:38 am

On 12/09/11 21:20, Philipp wrote:

Hi!

> Well, I need a programming project for a university course and this is

Let me start with discouraging you. ;) Don't do it.

Maybe you need to motivate your wish for "replaygain for audio tracks in
video files" a bit more, but basically, I see two points against it:

1. Real movies always have the right audio level, there's a universal
standard in the industry that's obeyed by mastering engineers. In
other words, replaygain is not needed here.

I'm only quoting Bob Katz on this, I've never mastered a Hollywood
production. ;)

2. Players like VLC have a normalize function. I don't know if it's
one-pass (on the fly, more like automated gain control) or two-pass,
but it basically solves your problem of audio levels at playback
time.

Given that (2) is universal wrt input formats, I see little to no
additional value in your proposed project.

> Scanning/tagging Since replaygain works on whole audio files I think I

Demuxing, yes.

> How easily this can be achieved I don't know.

There are special tools. If nothing helps, vlc and mplayer can do this.
mplayer with -dumpvideo and -dumpaudio, vlc with the transcode commands.

> After that, the scanning process should work as with any audio file.

Provided that the audio track supports meta data. Depending on the
container, you can embed almost everything from pcm to ogg, mp3, mp4/aac
and so on.

Depending on the container, it might be possible to add the meta data to
the muxed file.

> Playback Video players need to be aware of those tags, read the

See, this is where your problem starts. Too many formats, too many
players. This alone should be reason enough to move on and do something
useful instead.

That is why normalizing in the player's output chain (see (2) above) or
starting with decent levels (1) is the right approach.

> Other ideas I have are in short: - A CLI (using readline) connection

Hmm, IIRC, we have at least one oomidi user (sorry, forgot the name, a
guy from Russia) who's making heavy use of this.

> - A simple but hopefully sane mplayer GUI

smplayer? I don't know if mplayer already supports DVD menus. That's
something you could work on.

In any case:

http://www.mplayerhq.hu/design7/projects.html

Scroll down to "frontends".

> Another problem I might have is that most students in the course are

Create them an image to be used with virtualbox. ;)

Cheers

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Messages in current thread:
[LAD] Replaygain for video?, Philipp, (Fri Dec 9, 8:20 pm)
Re: [LAD] Replaygain for video?, Robin Gareus, (Sat Dec 10, 2:26 pm)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 10, 10:04 pm)
Re: [LAD] Replaygain for video?, Robin Gareus, (Sun Dec 11, 11:49 am)
Re: [LAD] Replaygain for video?, Fons Adriaensen, (Sun Dec 11, 12:19 pm)
Re: [LAD] Replaygain for video?, Robin Gareus, (Sun Dec 11, 1:28 pm)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 24, 12:11 pm)
Re: [LAD] Replaygain for video?, Jörn Nettingsmeier, (Sat Dec 10, 12:04 pm)
Re: [LAD] Replaygain for video?, Adrian Knoth, (Sat Dec 10, 10:38 am)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 10, 12:10 pm)
Re: [LAD] Replaygain for video?, Adrian Knoth, (Sat Dec 10, 2:02 pm)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 10, 8:42 pm)
Re: [LAD] Replaygain for video?, Fons Adriaensen, (Sat Dec 10, 2:22 pm)