Increasing audio volume on an MPG

[LDD]

Hi there, hoping someone can lend a hand.

I've been searching the internet for what feels like days now trying to get the audio in the MPG files I have to be increased.

They're ripped from DVD to VOB, then from VOB to MPG (to play nice with Plex) via MPEGTools in TMPGEnc. No loss in video quality which is great but for some reason when DVDShrink ripped the DVD the audio seems to have come out incredibly quiet.

So, going by what I've read the best option to add say 3db to the volume, ffmpeg is the best way to go however I can't get the commands right. It either deletes the audio entirely on the output file or increases the volume but then lowers quality to 128kbps 2ch audio (original is 5.1 448kbps).

If anyone can shed any light on this situation it would be great thanks

[Chris K]

You can try this but you need a recent FFmpeg version for it ...

ffmpeg.exe -i "input.mpg" -codec:v copy -f vob -codec:a ac3_fixed -b:a 448k -ar 48000 -ac 6 -af "volume=+3dB" -y "output.mpg"

Audio need to be re-encoded so there could be some quality loss.

[LDD]

Tried that but get the error 'unable to find suitable output format for 'vob''

[Chris K]

On what OS are you running? If on Windows, try the latest build from here http://ffmpeg.zeranoe.com/builds/

-f vob is required for muxing into mpg container.

[LDD]

Windows 7 64bit, latest build

Just retried and I must have had a typo previously because it's gone past that function now and gets stuck on the "volume=+3db" command saying it's unable to parse option '+3db'. I think I must just be missing something obvious here.

Thanks very much for your help

[Chris K]

Well, I'm on XP but get this with the given command line and latest zeranoe build ...

[Parsed_volume_0 @ 0258aca0] volume:(1.412538)(3.00dB) precision:float
[graph 0 input from stream 0:1 @ 0258a8e0] tb:1/48000 samplefmt:fltp
  ... samplerate:48000 chlayout:0x60f
[audio format for output stream 0:1 @ 0258a6c0] auto-inserting filter 'auto-inserted
  ... resampler 0' between the filter 'Parsed_volume_0' and the filter 'audio format
  ... for output stream 0:1'
[auto-inserted resampler 0 @ 0258a300] chl:5.1(side) fmt:fltp r:48000Hz -> chl:5.1
  ... fmt:s16p r:48000Hz

The current FFmpeg docs give a slightly different syntax (see examples) ...

http://ffmpeg.mplayerhq.hu/ffmpeg-filters.html#volume

[LDD]

That seems to have done the trick, using 'volume=2.0'. Thanks for your help

[hydra3333]

what was your final commandline syntax ?

[LDD]

ffmpeg -i input.mpg -codec:v copy -f vob -codec:a ac3 -b:a 448k -ar 48000 -ac 6 -af volume=3.0 -y output.mpg

The audio was incredibly quiet so adjusting volume to 3.0 worked a treat