[mythtv-users] MPEG4 bigger than MPEG2?

Michael T. Dean mtdean at thirdcontact.com
Sun Mar 11 12:28:46 UTC 2012

On 03/11/2012 04:57 AM, Karl Dietz wrote:
> On 10.03.2012 22:24, Raymond Wagner wrote:
>> On 3/10/2012 15:39, Ross Boylan wrote:
>>> I have trouble reconciling that statement with Tom Hayword's that
>>> "Re-muxing from MPEG2-TS to MPEG2-PS can save up to 20%."  Can anyone
>>> clarify?
>> 20% is a bit of a worst case value, but certain containers are just more
>> efficient than others.  TS containers are intended to be used for lossy
>> transmissions, and cases where you may want to start at any arbitrary
>> point.  That means there's padding, and lots of redundancy in the
>> metadata.  Where most containers might contain one header at the start
>> of the file, a TS container might intersperse them several times per second.
> keep in mind that auxiliary data gets removed in that step, too. (e.g.
> secondary audio channels,

and subtitle/caption tracks and ...

>   so you might end up with the audio description
> instead of the main track.<- anecdotal wisdom)

or an "empty" audio track.

If transcoding, make sure you enable:

Save original files after transcoding (globally)
If enabled and the transcoder is active, the original files will be 
renamed to .old once the transcoding is complete.

in mythtv-setup, then after transcoding, verify the new file, and if you 
decide it's good enough to replace the original, delete the 
<original_filename>.old file from the file system using normal 
(non-MythTV) file manager or rm.


More information about the mythtv-users mailing list