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twipley
21st June 2010, 19:31
Hello everybody. I have edited videos recently, here is a sample of the video info:

General
Complete name : D:\videos\camera32.avi
Format : AVI
Format/Info : Audio Video Interleave
File size : 1.05 MiB
Duration : 8s 909ms
Overall bit rate : 985 Kbps
Writing library : VirtualDub build 32817/release

Video
ID : 0
Format : MPEG-4 Visual
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : DX50
Codec ID/Hint : DivX 5
Duration : 8s 909ms
Bit rate : 819 Kbps
Width : 640 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate : 29.970 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.089
Stream size : 891 KiB (83%)
Writing library : DivX 5.0.0 (UTC 2002-03-04)

Audio
ID : 1
Format : MPEG Audio
Format version : Version 2
Format profile : Layer 3
Mode : Joint stereo
Mode extension : MS Stereo
Codec ID : 55
Codec ID/Hint : MP3
Duration : 8s 880ms
Bit rate mode : Variable
Bit rate : 146 Kbps
Channel(s) : 2 channels
Sampling rate : 22.05 KHz
Stream size : 158 KiB (15%)
Alignment : Split accross interleaves
Interleave, duration : 37 ms (1.10 video frame)
Interleave, preload duration : 876 ms


Played on my DivX-compatible DVD player, the sound is okay. But, when played through VLC or through latest K-Lite, there is a small delay (about a few seconds per half hour) in sound. To diagnose the issue, or just to try where the effect is coming from, I've tried changing the decoder for the audio in K-Lite's "ffdshow audio decoder configuration." More specifically, I've tried changing the decoder from "libmad" to other ones, but every other ones still present the issue. Weird thing, though, is that when set to "disabled," the audio still gets decoded.

Am am looking to further diagnose the issue. Someone (clsid) on another forum suggested that "It is possible the audio was just badly muxed. Remuxing it with VirtualDub might fix it. Just do a direct stream copy for both audio and video." -- However, it seems that the audio was not badly muxed as such a remuxing, once effectuated, did not fix the issue.

I believe the problem not to spring from the DVD player per se, as audio, uncompressed (PCM) using virtualdub, gets to play fine (that is, without any delay) on the PC (as well as on the DVP3960 DVD player). What is specifically strange, for it to be repeated, is that there is a delay between video and audio when those videos are played back on the PC, but not on the DivX player.

If you have any hints, suggestion, or diagnostic ideas, I'd greatly appreciate hearing any of those.

Thanks,
twipley

setarip_old
22nd June 2010, 08:03
Hi!

From within VirtualDub, try changing the audio to CBR (Constant Bitrate) .MP3 at 160kbps...

twipley
23rd June 2010, 01:27
Bad news... this is what it gives me:

http://i.imgur.com/HZLAh.png

(Lame MP3, having selected "show all formats" beforehand.)

setarip_old
23rd June 2010, 02:11
From within VirtualDubLameMP3 is not VirtualDub...

twipley
23rd June 2010, 14:48
Oh. Perhaps the option appeared there because I have K-Lite (full) installed?

What do you suggest then, choosing the "MPEG Layer-3" option for audio compression?


EDIT:

Doing so, it went from


Audio
ID : 1
Format : MPEG Audio
Format version : Version 2
Format profile : Layer 3
Mode : Joint stereo
Mode extension : Intensity Stereo + MS Stereo
Codec ID : 55
Codec ID/Hint : MP3
Duration : 4mn 57s
Bit rate mode : Constant
Bit rate : 56.0 Kbps
Channel(s) : 2 channels
Sampling rate : 22.05 KHz
Stream size : 1.98 MiB (4%)
Alignment : Split accross interleaves
Interleave, duration : 33 ms (1.00 video frame)
Interleave, preload duration : 502 ms



to


Audio
ID : 1
Format : MPEG Audio
Format version : Version 2
Format profile : Layer 3
Mode : Joint stereo
Mode extension : MS Stereo
Codec ID : 55
Codec ID/Hint : MP3
Duration : 4mn 57s
Bit rate mode : Variable
Bit rate : 148 Kbps
Channel(s) : 2 channels
Sampling rate : 22.05 KHz
Stream size : 5.27 MiB (10%)
Alignment : Split accross interleaves
Interleave, duration : 33 ms (1.00 video frame)
Interleave, preload duration : 862 ms



The problem seems fixed as of now. Have you guys any idea why there were delays using LAME and not once converted to MPEG layer-3?

Also, do you guys think the significantly reduced bit rate would reveal itself an issue concerning audio quality? I've converted directly from LAME ("22050 Hz, 256 kbps ABR, stereo" -- that is, the highest setting available) to the highest (that is, "56 kBit/s, 22 050 Hz, Stereo") available setting for MPEG Layer-3 -- has something important possibly been lost there in terms of audio quality, keeping in mind that the LAME encoding the second encoding came from was of the highest, almost pristine quality?

Also, any concerns about the high "preload duration," or is that just not to be cared about?

Thanks,
twipley

setarip_old
23rd June 2010, 22:31
The problem seems fixed as of now.You're welcome ;>}

twipley
25th June 2010, 16:52
That's the 862 ms prebuffer that's causing the delay, right? http://lame.sourceforge.net/tech-FAQ.txt

twipley
28th June 2010, 14:21
In fact I'll be staying with LAME.

Solution to this achieved in this other thread:
http://forum.doom9.org/showthread.php?p=1412084