MKV seek broken after re-encoding

Question

I have a few MKV files that need the title to be changed. My searching has led me to understand that re-encoding is the the easiest way to do so.

1. mediainfo on one of the files

   General
   Unique ID                                : 16743895095605599160700889077762303640 (0xC98C1C3DF6AACE6D7E0AE56F6D92698)
   Complete name                            : file1.mkv
   Format                                   : Matroska
   Format version                           : Version 2
   File size                                : 218 MiB
   Duration                                 : 18mn 23s
   Overall bit rate                         : 1 655 Kbps
   Movie name                               : Movie1
   Writing application                      : Lavf56.1.0
   Writing library                          : Lavf56.1.0
   WMFSDKNEEDED                             : 0.0.0.0000
   DEVICECONFORMANCETEMPLATE                : AP@L1
   WMFSDKVERSION                            : 11.0.5721.5265
   ISVBR                                    : 0
   ARTIST                                   : 
   COPYRIGHT                                : Copyright (c)
   
   Video    
   ID                                       : 1
   Format                                   : VC-1
   Format profile                           : Advanced@L1
   Codec ID                                 : V_MS/VFW/FOURCC / WVC1
   Codec ID/Hint                            : Microsoft
   Bit rate                                 : 1 558 Kbps
   Width                                    : 720 pixels
   Height                                   : 480 pixels
   Display aspect ratio                     : 3:2
   Frame rate mode                          : Variable
   Standard                                 : NTSC
   Color space                              : YUV
   Chroma subsampling                       : 4:2:0
   Bit depth                                : 8 bits
   Scan type                                : Progressive
   Compression mode                         : Lossy
   Default                                  : No
   Forced                                   : No
   
   Audio
   ID                                       : 2
   Format                                   : WMA
   Format version                           : Version 2
   Codec ID                                 : A_MS/ACM / 161
   Codec ID/Info                            : Windows Media Audio
   Duration                                 : 18mn 23s
   Bit rate                                 : 64.0 Kbps
   Channel(s)                               : 2 channels
   Sampling rate                            : 48.0 KHz
   Bit depth                                : 16 bits
   Stream size                              : 8.42 MiB (4%)
   Default                                  : No
   Forced                                   : No
   

2. I used a simple codec copy command with a title tag

   avconv -i file1.mkv -c:v copy -c:a copy -metadata title='title1' file1-retitled.mkv
   

However, there is an issue when I seek the new video - it appears all blotchy (big, dark and coloured squares) for a couple of seconds and then becomes all right. I have tried the seek with different video players. The input file has no seek issues - works perfectly fine (it might be noted that the input files had themselves been cut from other video files using avconv).

How do I fix this issue?

Answer 1

RE-encoding is likely to result in a loss of quality but by using the c:v copy and c:a copy switches, you are only moving the data from one container to another this should not result in any loss of quality. My best guess for the problem you are experiencing is issues with the V_MS/VFW/FOURCC / WVC1 Video stream. It might be related to this bug: https://bugzilla.libav.org/show_bug.cgi?id=600

However:

Since the original file file1.mkv has no problems the easiest way is to simply use mkvpropedit to edit the properties of the mkv file for example mkvpropedit file1.mkv --set "title=New Title"

If it's not installed you can install the package with:

sudo apt-get install mkvtoolnix

Source: Experience

More Info: https://mkvtoolnix.download/doc/mkvpropedit.html