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Permlink Replies: 4 - Pages: 1 - Last Post: Aug 2, 2011 6:07 AM Last Post By: ethanb
Phorat

Posts: 163
Registered: 04/20/10
Adjust audio gain when transcoding?
Posted: Apr 20, 2010 12:21 PM
 
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Running: Vuze 4.4.0.0
On: Windows Vista Home Premium x64
TiVo: HD XL

While transcoding works well, I have noticed that the audio is sometimes quite low in volume, requiring me to crank up the volume on my TV when viewing the show with my TiVo. Is there some way in FFmpeg to adjust the audio gain that is used by Vuze when transcoding? I know how to tweak the Vuzexcode profile for my TiVo, and have read what I could find online about FFmpeg, but I have had no success so far in finding a way to up the audio volume in the transcoded file.
Phorat

Posts: 163
Registered: 04/20/10
Re: Adjust audio gain when transcoding?
Posted: Apr 26, 2010 9:44 AM   in response to: Phorat in response to: Phorat
 
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Well, it appears that I, a "Newbie," already know at least as much as, if not more than, the "Masters" on this forum.

Audio gain continues to be a problem in Vuze's rendering of FFmpeg. However, I don't think that FFmpeg has in its current suite of flags a setting for audio gain. Bummer.
Phorat

Posts: 163
Registered: 04/20/10
Re: Adjust audio gain when transcoding?
Posted: Apr 26, 2010 5:10 PM   in response to: Phorat in response to: Phorat
 
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Eureka! After much reading and searching on Google, I found an answer to my problem! It turns out that FFmpeg (the transcode protocol used by Vuze) has an option to adjust the volume of the audio codec. The flag for this option is "-vol." The default setting of "-vol" for FFmpeg is 256; in other words, if the "-vol" flag is not set, the default value for "-vol" in "-acodec" is 256. For whatever reason, this default value is WAY too low for a lot of devices, including TiVo.

After much experimenting, I found that a setting of "-vol 2048" gives about a "normal" volume setting in the transcoded file.

EDIT - 2048 was a tad too loud, so I finally wound up using a setting of 1024. This value provides plenty of audio gain without being overpowering. By the way, the change is slow, so I think using integer multiples of 256 is probably the way to go for this setting.

I realized that perhaps there aren't a lot of people who know about how Vuze determines what codecs, etc. to use when transcoding an AV file for transferring to a device like a TiVo or a PS3, etc. Here's the scoop:

The settings for transcoding are device-specific, and are stored in a folder within "C:\Users\<user>\AppData\Roaming\Azureus\plugins\vuzexcode\profiles" (on Vista/Windows 7) or "C:\Documents and Settings\<user>\Application Data\Azureus\plugins\vuzexcode\profiles" (on Windows XP). Within "..\profiles" are several small files (basically, text files of file type ".properties") that have commands that relate to how FFmpeg builds the transcoded file that will be played on your device. The files may be opened and edited in a text editor (like Notepad). If you're editing your device profile, make sure that it is saved as file type ".properties" after you're done making changes.

There are two main command lines: one that determines the video codec and its settings, and one for the audio codec and its corresponding values. The two command lines look something like this (these are for the HD TiVo, and includes my change to the audio argument):

video-args= -vcodec mpeg2video -b 20000k -maxrate 35000k -bufsize 4096k -f vob

audio-args=-acodec ac3 -vol 2048

In the "audio-args" line, I have added "-vol 2048," which means to boost the volume up from its default setting of 256 to that of 2048. Note that I have used a power of 2 - this may or may not be necessary for FFmpeg to understand your setting. Some writers on the subject have said so, but I thought that I got results at non-integer factors of 256 as well.

At any rate, there you have it.

Edited by: Phorat on Apr 26, 2010 11:00 PM

Edited by: Phorat on Apr 26, 2010 11:04 PM
johnson

Posts: 1
Registered: 06/08/10
Re: Adjust audio gain when transcoding?
Posted: Jun 8, 2010 1:53 AM   in response to: Phorat in response to: Phorat
 
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I have not TiVo,but I have a psp 3000.I use ddvideo psp video converter gain , It supports audio gain,video gain ,mp3gain and help me put my video or musics with low in volume improve their level to 115 db maximum.and make my video and audio file more clearer,
they have many product for video converter,you can visit their website to search a suitable software for you.

hope it is useful for you.

Edited by: johnson on Jun 8, 2010 1:56 AM
ethanb

Posts: 2
Registered: 08/02/11
Re: Adjust audio gain when transcoding?
Posted: Aug 2, 2011 6:07 AM   in response to: Phorat in response to: Phorat
 
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Thanks Phorat for the great info.
I was hoping somebody might be able to help me make this work on my mac - I can't find any files with any values at all. Looked in libraries, preferences, everything.
Anybody?
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