[MPlayer-users] Trouble mencoding a large DVB (1080i) grab

[MichaelM]

Nico Sabbi wrote:
> MichaelM wrote:
> 
>> Hey all.
>> I've been using mencoder to transcode DVB grabs to avis, and it's been
>> working just fine (will a little manual tweaking to get the -ss and
>> -endpos numbers just right).
>> Since seeking a TS is tricky, I convert the TS to a regular mpeg2 file
>> as follows:
>>
>> mencoder dump.ts -oac copy -ovc copy -of mpeg -o dump.mpg
>>
>> Then I run through the stream with mplayer to get my start and endpos
>> numbers (to cut out commercials), and then use mencoder again to chop up
>> the stream (with -ss and -endpos).
>>
>> I recently got a new harddisk, so am playing with large HDTV streams. I
>> grabbed 9GB worth (a bit more than an hour), and started doing my thing.
>>
>> Problem is (for both mplayer and mencoder), is that I cannot use -ss
>> past 749.9 seconds (though 749.8 works fine). If I run the file from the
>> start, I can seek fine with the arrow keys, but specifying a number
>> beyond 749.9, mencoder exits with the following:
>>  
>>
> 
> for mpeg never use -ss, use -sb <BYTE_OFFSET> instead
> 

Neat, -sb seems to work. Is there an easy way to calculate the values ?
ATM I've got start times. Will it really be a matter of calculating
percentages based on the file size and length ?