[mythtv-users] Problem with MPEG-4 transcoded file (no bitrate or duration)
John Pilkington
johnpilk222 at gmail.com
Mon May 13 08:04:55 UTC 2019
On 13/05/2019 05:12, mythtv at kosowsky.org wrote:
> mythtv at kosowsky.org wrote at about 00:00:23 -0400 on Monday, May 13, 2019:
> > In my old mythtv box (v24), I had no problem transcoding recordings to
> > MPEG4 and then editing (i.e. cutting) the video in the mythtv editor.
> >
> > For example, a transcoded and edited file, shows up under ffmpeg -i
> > as:
> > Duration: 00:19:16.47, start: 0.033000, bitrate: 1411 kb/s
> > Stream #0:0: Video: mpeg4 (Simple Profile) (DIVX / 0x58564944), yuv420p, 720x480 [SAR 1:1 DAR 3:2], SAR 32:27 DAR 16:9, 29.97 fps, 29.97 tbr, 1k tbn, 30k tbc
> > Stream #0:1: Audio: mp3 (LAME / 0x454D414C), 48000 Hz, stereo, s16p, 1411 kb/s
> >
> > Under v29.1, when I transcode to mpeg4, the file seems to transcode (and compress) properly and I have no problem playing it.
> > But, when I try to edit it, the timestamps are all wrong, so that when I use the editor to cut and re-transcode, the cut list is not properly applied and the file is not spliced together properly.
> > When I run 'ffmpeg -i' I see that both the "Duration" and the "bitrate" are 'N/A', presumably explaining why the timestamps are wrong.
> > Duration: N/A, start: 60704.885000, bitrate: N/A
> > Stream #0:0: Video: mpeg4 (Simple Profile) (DIVX / 0x58564944), yuv420p, 704x480 [SAR 1:1 DAR 22:15], SAR 40:33 DAR 16:9, 29.97 fps, 29.97 tbr, 1k tbn, 30k tbc
> > Stream #0:1: Audio: mp3 (LAME / 0x454D414C), 48000 Hz, stereo, s16p, 1411 kb/s
> >
> > I tried using 'mythcommflag --rebuild --file' to rebuild the seektable (which has saved me other times), but id had no effect.
> >
> > Is there something broken with mythtranscode that causes the file to create transcodings without defined durations or timestamps?
> >
> > Again, I never had the problem in (much) older version of mythtv...
> >
> > Thanks,
> > Jeff
>
> Note the transcoding profile I use is as follows:
> Autodetect from MPEG2
> Profile name: MPEG2
> Enable auto-transcode after recording: yes
> Width: 720
> Height: 480
> Video Compression: MPEG-4
> Bitrate (kb/s): 3300
> Maximum quality: 2
> Minimum quality: 15
> Max quality difference between frames: 3
> Scale bitrate for frame size: No
> Enable high-quality recording: Yes
> Enable 4MV encoding: Yes
> Enable interlaced DCT encoding: No
> Enable interlaced motion estimation: No
> Number of threads: 4
>
> Audio Quality: MP3
I have never used mythtranscode with a format like that, but it seems
likely that your problem is actually an incompatibility with
mythcommflag --rebuild, or its equivalent within mythtranscode.
It's not clear to me why you can't do the editing before transcoding,
either directly to MPEG-4 or using mythtranscode --mpeg2 first.
John P
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