[mythtv-users] Lossless Cut (mythcommflag vs mythtranscode)

[Angela]

> All three tools (the recorder, mythcommflag --rebuild, and mythtranscode
--
> buildindex) produce seektables in the same place, namely the recordedseek
> table for recordings and the filemarkup table for videos.  If mythcommflag
is
> not producing any seektable entries, one possibility is that the
underlying
> ffmpeg is crashing on the file, which is not unheard of.  You might be
able to
> detect this by running it from the debugger.  If not, it would help to get
> access to the video file in question.

I was playing around with the newest lossless cut scripts (PPAs as 20130506)
and noticed that the cut video was always 3-4 keyframes earlier.
Thought I could fix it with mythcommflag and mythtranscode (0.26-fixes as
20130503), so I rerun both and noticed with an interlaced recording that
mythtranscode sets the marks to double the keyframes.
Seektable made with mythtranscode cannot be used for lossless_cut.

What could be the cause that the output of lossless_cut is 3-4 keyframes too
early ?
I noticed on the same file, when using a 1 minute cut, the output file
duration is correct, when it is around 40 minutes the duration in the mkv
file is more than 17 hours. 
This could be easily fixed with http://www.mkvrepair.com/, any idea what
could be the cause ?

Angela

Mythcommflag:
	10017	2012-09-29 01:55:00	0	0	9
	10017	2012-09-29 01:55:00	28	2122708	9
	10017	2012-09-29 01:55:00	56	3327788	9
	10017	2012-09-29 01:55:00	84	4577424	9
	10017	2012-09-29 01:55:00	112	5760508	9
	10017	2012-09-29 01:55:00	140	6996232	9
	10017	2012-09-29 01:55:00	172	8274444	9
	10017	2012-09-29 01:55:00	200	9378192	9
	10017	2012-09-29 01:55:00	240	10984088	9
	10017	2012-09-29 01:55:00	268	12396156	9
	10017	2012-09-29 01:55:00	296	13715164	9
	10017	2012-09-29 01:55:00	324	15650812	9
	10017	2012-09-29 01:55:00	368	18347296	9
	10017	2012-09-29 01:55:00	388	19492968	9
	10017	2012-09-29 01:55:00	424	21757052	9

Mythtranscode:
	10017	2012-09-29 01:55:00	55	939812	9
	10017	2012-09-29 01:55:00	111	2122708	9
	10017	2012-09-29 01:55:00	167	3327788	9
	10017	2012-09-29 01:55:00	223	4577424	9
	10017	2012-09-29 01:55:00	279	5760508	9
	10017	2012-09-29 01:55:00	335	6996232	9
	10017	2012-09-29 01:55:00	399	8274444	9
	10017	2012-09-29 01:55:00	455	9378192	9

<track type="Video">
<ID>60 (0x3C)</ID>
<Menu_ID>1 (0x1)</Menu_ID>
<Format>AVC</Format>
<Format_Info>Advanced Video Codec</Format_Info>
<Format_profile>High at L4.0</Format_profile>
<Format_settings__CABAC>Yes</Format_settings__CABAC>
<Format_settings__ReFrames>3 frames</Format_settings__ReFrames>
<Format_settings__GOP>M=4, N=28</Format_settings__GOP>
<Codec_ID>27</Codec_ID>
<Duration>57mn 57s</Duration>
<Bit_rate>8 534 Kbps</Bit_rate>
<Width>1 920 pixels</Width>
<Height>1 080 pixels</Height>
<Display_aspect_ratio>16:9</Display_aspect_ratio>
<Frame_rate>25.000 fps</Frame_rate>
<Standard>Component</Standard>
<Color_space>YUV</Color_space>
<Chroma_subsampling>4:2:0</Chroma_subsampling>
<Bit_depth>8 bits</Bit_depth>
<Scan_type>Interlaced</Scan_type>
<Scan_order>Top Field First</Scan_order>
<Bits__Pixel_Frame_>0.165</Bits__Pixel_Frame_>
<Stream_size>3.46 GiB (91%)</Stream_size>
<Color_primaries>BT.709</Color_primaries>
<Transfer_characteristics>BT.709</Transfer_characteristics>
<Matrix_coefficients>BT.709</Matrix_coefficients>
</track>