mkv A_AC3 to AC3 DVD sound, help

[Malick]

It is my understanding that many MKV hi-def videos have A_AC3 sound. For some reason the audio is 3x lower with MKV videos than DVD videos. Can someone please help me to convert MKV A_AC3 audio to regular DVD AC3 audio?

I made a test: I extract audio from MKV and replaced with regulad DVD audio (picture and sound were not in sync ofcorse) and the audio WAS loud as it supposed to be. So the problem is with MKV audios - they just are not the same as DVD audios.

[tebasuna51]

The audio is the same. The problem is with your players.

[Malick]

i use regular windows media player

dvd with ac3 sound - sound is loud (like i want)
mkv with a_ac3 sound - sound is low (not what i want)
mkv with ac3 (a_ac3 stripped first and replaced with ac3 taken from dvd) - sound is loud (like i want)

i have dvd and mkv with the same movie. So the problem must be with the a_ac3 sound

[tebasuna51]

mkv with ac3 (a_ac3 stripped first and replaced with ac3 taken from dvd) - sound is loud (like i want)

i have dvd and mkv with the same movie. So the problem must be with the a_ac3 sound

Well, maybe the a_ac3 is wrong. But you have the solution use the ac3 from the DVD.

[Malick]

if i take the ac3 from DVD and mux it to mkv the audio is not in sync, very hard to put it in sync. Besides, i have many mkv videos. I still need to convert the mkv audio to DVD audio somehow.

[tebasuna51]

Please send a sample of your a_ac3 to see a method to transcode.

You can use a hex editor to take a fragment or:
VirtualDub -> Tools -> Hex Editor -> File -> Open... your a_ac3 file, Edit -> Extract Segment... -> (Address: 0, Length: 10000) Ok and save like segment.ac3.

Use http://www.mytempdir.com/ to host this file.

[Malick]

it took exacly 25 seconds from each in the beginning of movie

audio from DVD - http://www.mytempdir.com/1331614
audio from MKV - http://www.mytempdir.com/1331619

[tebasuna51]

it took exacly 25 seconds from each in the beginning of movie
If you want you need only delay 4.118 sec. (use DelayCut) the a_vob.ac3 to sync with mkv video.

But, warning, the a_vob volume is 7 dB below (RMS: -56.09dB.) than the a_mkv volume (RMS: -49.12dB):
Analyzed 100%. a_vob.ac3

[Ch 0] Maximum: -36.44dB. Average: -61.80dB. RMS: -54.78dB.
[Ch 1] Maximum: -37.27dB. Average: -62.29dB. RMS: -55.35dB.
[Ch 2] Maximum: -31.75dB. Average: -58.78dB. RMS: -51.53dB.
[Ch 3] Maximum:-133.12dB. Average:-187.90dB. RMS:-100.00dB.
[Ch 4] Maximum: -42.70dB. Average: -67.87dB. RMS: -60.83dB.
[Ch 5] Maximum: -42.02dB. Average: -68.76dB. RMS: -61.71dB.

[All ch.] Maximum:-31.75dB. Average:-64.68dB. RMS:-56.09dB.
-----------------------------------------------------------
Analyzed 100%. a_mkv.ac3

[Ch 0] Maximum: -29.58dB. Average: -54.81dB. RMS:-47.83dB.
[Ch 1] Maximum: -30.46dB. Average: -55.29dB. RMS:-48.40dB.
[Ch 2] Maximum: -24.65dB. Average: -51.79dB. RMS:-44.55dB.
[Ch 3] Maximum:-109.03dB. Average:-130.96dB. RMS:-99.97dB.
[Ch 4] Maximum: -35.89dB. Average: -60.88dB. RMS:-53.89dB.
[Ch 5] Maximum: -35.10dB. Average: -61.77dB. RMS:-54.77dB.

[All ch.] Maximum:-24.65dB. Average:-57.69dB. RMS:-49.12dB

There are also some differences between ac3 headers:
File to analyze: D:\INTERNET\a_vob.ac3
SampleRate 0 : 48000 KHz.
BitRate 15 : 448 Kb/s.
Version (bsid) 8 : Standard.
Bit Stream mode (bsmod) 0 : main audio service: complete main (CM)
Audio coding mode (acmod) 7 : 3/2 - L, C, R, SL, SR
Center Mix Level 0 : 0.707 (-3.0 dB)
Surround Mix Level 0 : 0.707 (-3 dB)
Low frequency effects channel 1 : Present
Dialogue normalization - 27 dB
RF atenuattion 6,01 dB Frame: 1
Languaje 0 : Not present
Audio Production Mixlevel 105 dB SPL
Audio Production Room type 1 : large room, X curve monitor
CopyRight bit 1
Original bit 1
Timecode1 0 : Not present
Timecode2 0 : Not present
Additional Bsi 0 : Not present
Block switch flags 0
Dither flags 31
Dynamic Range gain 6,01 dB Frame: 1
----------------------------------------------------------
File length : 1401344 bytes.
Valid Frames : 782
Duration : 25,024 seconds. ( 0 h. 0 m. 25,024 s.)
RF Ov. Pr. min/max : 4,85 / 6,01 dB
Dyn. Range min/max : 4,85 / 6,01 dB
----------------------------------------------------------
==========================================================
File to analyze: D:\INTERNET\00\a_mkv.ac3
SampleRate 0 : 48000 KHz.
BitRate 18 : 640 Kb/s.
Version (bsid) 8 : Standard.
Bit Stream mode (bsmod) 0 : main audio service: complete main (CM)
Audio coding mode (acmod) 7 : 3/2 - L, C, R, SL, SR
Center Mix Level 0 : 0.707 (-3.0 dB)
Surround Mix Level 0 : 0.707 (-3 dB)
Low frequency effects channel 1 : Present
Dialogue normalization - 31 dB
RF atenuattion 0 : Not present
Languaje 0 : Not present
Audio Production Info 0 : Not present
CopyRight bit 0
Original bit 1
Timecode1 0 : Not present
Timecode2 0 : Not present
Additional Bsi 0 : Not present
Block switch flags 0
Dither flags 31
Dynamic Range Info 0 : Not present
----------------------------------------------------------
File length : 2001920 bytes.
Valid Frames : 782
Duration : 25,024 seconds. ( 0 h. 0 m. 25,024 s.)

Maybe theese differences can affect your players adjust, but I can say you than, using the same filters and settings, the mkv sound is loud than vob sound.

[Malick]

how did you mesure 4,118s? Its very accurate, thanx.

To me its the other way around. vob is 3x louder than mkv

i knew these ac3 were diferent. So...can someone PLEASE help me to convert a_mkv.ac3 equal to a_vob.ac3. I dont care if a_vob is lower in quality, i just need that a_mkv has a_vob sound (regular DVD sound)

[tebasuna51]

i knew these ac3 were diferent. So...can someone PLEASE help me to convert a_mkv.ac3 equal to a_vob.ac3. I dont care if a_vob is lower in quality, i just need that a_mkv has a_vob sound (regular DVD sound)
Here is an a_mkv_new.ac3 (http://www.mytempdir.com/1331802), obtained re-encoding a_mkv.ac3 with the free encoder Aften and bitrate 448, dialnorm -27, DynRange 'standard film' like the a_vob.ac3

If you think this can solve your problem say me which method prefer (if you have already any soft installed) to do with Aften:
- AviSynth-SoundOut-NicAudio
- AviSynth-BeHappy/Bepipe-NicAudio (also .NET Framework 2.0 required)
- Belight-BeSweet-Azid
- Foobar2000-foo_ac3.dll

[Malick]

I muxed your a_mkv_new.ac3 to the original 25s mkv file - the audio is still low. I just dont get it :(

Again, how did u measure the 4,118s earlier?

[tebasuna51]

I muxed your a_mkv_new.ac3 to the original 25s mkv file - the audio is still low. I just dont get it
I say you in the first post, is a player problem. Don't use Windows Media Player, use vlc or BsPlayer-ffdshow.
Again, how did u measure the 4,118s earlier?
I decode to wav the samples, I select and compare the same channel in both with an audio editor (GoldWave, Audacity, ...).

[Malick]

ok i used bsplayer-ffdshow - still i have the same problem

[tebasuna51]

ok i used bsplayer-ffdshow - still i have the same problem
Is not possible, the a_mkv.ac3 is clearly loud (7 dB) than a_vob.ac3.

You can see the vu-meters in 'ffdshow audio decoder configuration' -> 'Volume' -> 'Show current volume levels'

[Malick]

if i use the vob and new_mkv (audio by you) with any player - new_mkv has 3x lower volume. So that means that vob audio and new_mkv audio ARE NOT the same :(

[tebasuna51]

if i use the vob and new_mkv (audio by you) with any player - new_mkv has 3x lower volume. So that means that vob audio and new_mkv audio ARE NOT the same
Maybe you have a different DirectShow filter configuration used when you play a .VOB file than when play only .ac3 or .mkv.

You need compare the two .ac3 (extracted from mkv and vob).