audio sync problem with HDTV .m2t to mp4

[avramd]

Hello,

I'm trying to transcode a pure HDTV stream to .mp4, and the audio comes out abou 1/4 second behind the video. I'm using all defaults, I just drag the file onto the summary well, select the MP4 .mov quick preset, change the output filename, and press Encode.

I have tried this with the source filename ending in .mpg as well as .m2t (same file, just different name). EyeTV names the files ".mpg" by default. This is the one that works best, with the only problem being the audio delay described above. One thing I notice though is that it takes a long time for ffmpegX to analyze the source file when I drop it in the well.

When I rename the file to .m2t, the initial source analysis is quick, but the resultant video is horrible. It seems to be extremely processor intensive. my dual-core mac mini drops frames all over the place, and when it's not dropping frames, the video appears to be running significantly slower than the audio - perhaps even half speed.

I have searched, and haven't found any other related threads. Can anyone help?

Thanks,
Avram

[major]

As a test, try converting to "DivX mencoder" to see if it works any better.

[rack]

I have a somewhat related question. I have an HDTV Mpeg2 transport stream at 59 fps (720p). I'd like to convert it to h.264 at 24 fps. Is this possible? When I try with a test clip using the "h.264 x264" preset, the result is very choppy.

Using "DivX mencoder" seems to give a decent result.

[avramd]

Well, I am trying to do as you've asked, but it is not making any progress. It has been running for well over 2 hrs on a 3 minute clip, and it hasn't even started transcoding yet.

One thing I notice is that after selecting the preset, it has chosen 1920x1088 as the output resolution, and the status message says "Movie-Aspect is 1.78:1 - prescaling to correct movie aspect." Does this mean it is pre-processing the stream before encoding it? And even so, why would a 3 min clip take 3 hours?

Here is the current process information if it helps:

Encoding started on Mon May 8 13:10:01 EDT 2006
MEncoder dev-CVS-060307-04:23-4.0.1 (C) 2000-2006 MPlayer Team
FIXME:Hardenabling SSE and SSE2 without detection
Mac OSX static build for ffmpegX
CPU: Intel (Family: 6, Stepping: 8)
CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2
success: format: 0 data: 0x0 - 0x19e39f5c
TS file format detected.
DEMUX OPEN, AUDIO_ID: 0, VIDEO_ID: -1, SUBTITLE_ID: -2,
PROBING UP TO 2000000, PROG: 0
VIDEO MPEG2(pid=49)NO AUDIO! NO SUBS (yet)! PROGRAM N. 0
Opened TS demuxer, audio: ffffffff(pid 0), video: 10000002(pid 49)...POS=0, PROBE=2000000
VIDEO: MPEG2 1920x1080 (aspect 3) 29.970 fps 65000.0 kbps (8125.0 kbyte/s)
[V] filefmt:29 fourcc:0x10000002 size:1920x1080 fps:29.97 ftime:=0.0334
Opening video filter: [expand osd=1]
The selected video_out device is incompatible with this codec.
Try adding the scale filter, e.g. -vf spp,scale instead of -vf spp.
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [scale w=1920 h=1088]
================================================== ========================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 1920 x 1080 (preferred colorspace: Mpeg PES)
VDecoder init failed
Opening video decoder: [libmpeg2] MPEG 1/2 Video decoder libmpeg2-v0.4.0b
Selected video codec: [mpeg12] vfm: libmpeg2 (MPEG-1 or 2 (libmpeg2))
================================================== ========================
Forcing output fourcc to 58564944 [DIVX]
VDec: vo config request - 1920 x 1080 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.

[major]

Can you send me the clip? (try to use yousendit.com, my email is major4@mac.com).

[major]

I have a somewhat related question. I have an HDTV Mpeg2 transport stream at 59 fps (720p). I'd like to convert it to h.264 at 24 fps. Is this possible? When I try with a test clip using the "h.264 x264" preset, the result is very choppy.

Using "DivX mencoder" seems to give a decent result.

You should convert to 29.97 for best results (ie. divide the framerate by 2).

[rack]

You should convert to 29.97 for best results (ie. divide the framerate by 2).

Thank you!

[avramd]

Ok, I sent you a clip. This is a clip of the clip b/c its a 1080i stream and that's all that would fit through yousendit.

[avramd]

Hey Major,

DId you receive the clip I sent?

Thanks,
Avram

[oediv]

I also have desynchronized sound with most conversions I make.
Usually it's avi to mp4 (see attached preset), I check Decode with QT to force both audio and video conversion.

last.ffx