Hi,

Although it does not seem to be a Kdenlive issue, I decided to start here asking for help to track down the exact problem.

== Intro ==
I have a recording of a mounted (B) and handheld camcorder (D) and a seperate audio recording from CD (A). The audio was cut, so that it starts at the same time as the video. The video of the mounted camcorder was processed with filters of ffmpeg (C).

== Problem ==
When working in Kdenlive, the A/V delay (audio lags) between A and B/C increases up to 2.5 secs after 25 mins. Since it is a video of a live performance, it is very noticeable and undesirable. There seems to be no problem with D.

== Oddity ==
The source material is fine. I assume this because of two reasons:
1. The audio track of B and A are exactly in sync when opened in Audacity.
2. MPC-HC is able to resync A and C (by delaying audio or adjusting the play speed of video) most of the time, not A and B, though.

== Technical details ==
B was acquired by ripping the DVD-RW (with testdisk) which was accidentally not finalized. This resulted in several MPEG files that were simply concatenated together afterwards. This file was filtered (sharpen and stuff) and the result is C.

copy /b file0001.mpg+file0002.mpg+...+fileNNNN.mpg merged.mpg (86 files, B)

Input #0, mpeg, from 'file0001.mpg':
. Duration: 00:00:20.60, start: 0.262222, bitrate: 4758 kb/s
. . Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 704x576 [SAR 12:11 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 50 tbc
. . Stream #0:1[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 256 kb/s

Input #0, mpeg, from 'file0002.mpg':
. Duration: 00:00:21.91, start: 0.109489, bitrate: 4469 kb/s
. . Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 704x576 [SAR 12:11 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 50 tbc
. . Stream #0:1[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 256 kb/s

(notice the 'start' info)

ffmpeg -i merged.mpg -c copy merged-fix.mkv

ffmpeg -i merged-fix.mkv -vf ... -an -crf 0 filtered.mkv (C)

Thanks a lot for your help.
Adi


Addendum 31.05.2013:
I reripped the video from the image with the audio track enabled (ffmpeg v1.2). It works well on its own, but there's random delay when playing in Kdenlive. The track thumbnails clearly indicate that it SHOULD BE IN SYNC, though! See: http://postimg.org/image/y3i9qzao7/full/

Please help, I've been desperatly trying to find the cause, but I have no success...