[mythtv-users] MPEG-2 to MPEG-4 Transcoding comparisons

[James L. Paul]

Clif Deanhardt wrote:
> Would someone who's using .12 to transcode PVR-250 MPEG-2s into MPEG-4s like
> to compare notes on compression rates?  I'm trying to get a handle on
> whether I've got mine set up optimally and I'm a bit of a noob at setting
> this thing up.
> 
> With the exception of a apparition when I first started using it, every one
> of my 1hr shows records at 3.7gb and after transcoding it's 2.2gb,
> regardless of the type of show or number of colors or quantity of movement.

I wonder... Is the quality of a 3.7G MPEG2 file transcoded to 2.2GB 
MPEG4 better or worse than just encoding the original MPEG2 at 2.2G in 
the first place? I have trouble believing it's better quality and worth 
the effort, unless for some reason you really want the results as MPEG4.

> Likewise, every one of my half hour shows records at 1.8gb and transcodes to
> 1.1gb.

My PVR-250 bitrate is set to result in 1 hour for 1.8G and looks 
absolutely great, better than VHS to my eye. I just keep the MPEG2 and 
prefer not to transcode at all. Then again, I have little use for MPEG4.

> Is anyone else similarly set up?  What numbers are you getting?
> 
> Thanx!
> 
> Clif
> 
> 
> My settings:
> 
> ----------------------------
> MPEG-2 ENCODERS / DEFAULT
> ----------------------------
>    Width/Height: 480x480
> 
>    Codec: MPEG-2 HARDWARE ENCODER
>    Stream: MPEG-2 PS
>    Aspect: 4:3
>    Bitrate: 4500
>    Max Bitrate: 6000
> 
>    Codec: MPEG-2 HARDWARE ENCODER
>    SampleRate: 32000
>    Type: Layer II
>    Bitrate: 384kbps
> 
> ----------------------------
> TRANSCODERS / MPEG2
> ----------------------------
> 
>    Width/Height: 480x480
> 
>    Codec: MPEG-4
>    Bitrate: 2200
>    Max Quality: 2
>    Min Quality: 15
>    Max Quality Difference Between Frames: 3
>    Scale Bitrate for Frame Size: Selected
>    Enable High Quality encoding: Not Selected
>    Enable 4MV: Not Selected
> 
>    Codec: MP3
>    SampleRate: 32000
>    Quality 7
> 
> ----------------------------
> GENERAL
> ----------------------------
> It's configured to automatically detect commercials, but not to skip them.
> And the resulting, compressed files still have the commercials in them.
> 
> 
> 
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