[mythtvnz] Cutting H.264 DVB-T files with ffmpeg without transcoding

[Nick Rout]

On Sat, Jul 24, 2010 at 9:02 PM, Ross and Jemima Knudsen
<ross.jemima at gmail.com> wrote:
> On 24/07/2010 12:38 p.m., David Moore wrote:
>>
>> I've used VB a fair bit also but I don't think it's a good idea to rely
>> on something which isn't pretty standard in Ubuntu for portability
>> reasons. Turns out sql in bash is really simple. Just echo the sql
>> commands through a pipe to mysql and catch the results. Dead easy. :-)
>> Hardest thing will be understanding which tables need updating.
>> Recordedseek and recordedmarkup are the ones I know of so far.
>>
>
> You'd just want to drop all the markings for the particular recording
> after doing any of the transcoding as potentially the timestamps may be
> altered.  So something like:
> 'delete from `recordedmarkup` where `chanid` = X and `starttime` = Y'
> and 'delete from `recordedseek` where `chanid` = X and `starttime` = Y
>
> http://www.mythtv.org/wiki/Recordedmarkup_table
> http://www.mythtv.org/wiki/Recordedseek_table
>
> To fix the entries in the seek table just take the lazy way out and use
> one of the methods here:
> http://www.mythtv.org/wiki/Repairing_the_Seektable
>
> PS I thought that mono libraries were installed as default on Ubuntu?...
>> Actually looks like the trickiest thing is handling the cuts. Myth cuts
>> in recordedmarkup table are in frames whereas ffmpeg uses times so need
>> to do some maths to convert frame to time. Bash doesn't do floating
>> point maths but there is a linux utility called bc to do this so that's
>> no problem. Could be a problem with cut accuracy however. I had a look
>> at one of my recordings last night and it seems that the time myth shows
>> for the cut points is not exactly equal to the cut point frame number x
>> 25 (fps). I'm guessing there might be some issue with the start time for
>> the recording but not sure yet.
>>
>>
>
> Maybe using Avidemux might be feasible if you can get it to work on the
> commandline.  It uses frame numbers (I believe).
>


avidemux works from the commandline. It uses frame numbers.