LinHES Forums :: View topic - transcoding increases file size ?

mpeg4 is effectively divx

What are the settings in the default transcoding profile from mpeg2 to mpeg4? Make sure the resolution matches that which you used to record in the first place. And you can vary the bitrate used as well.

I transcode my MPEG2 to MPEG4 all the time and it halfs it.

Just a thought - are you sure the original file was MPEG2? Maybe it was already transcoded?

here is the settings for the file i transcoded (according to media player classic)

Quote:

here is the settings for the file i transcoded (according to media player classic)

OK, but what are the settings in the default profile itself (Setup/Recording profiles/transcoders etc)? What bitrate is it using for example?

Although must admits its pretty odd...

Alright - so how long (timewise) is the transcoded file? 2.4Gb at 2200kbps should be approx 2 hrs 24 mins or thereabouts (1Gb/hr). If thats the length then the coding is about right. If not, then ?

Author:	declanh [ Tue Jan 24, 2006 3:23 pm ]
Post subject:	transcoding increases file size ?
Not tried it before (till tonight) - I transcoded a film using the option from withing the playback menu. The Source video i transcoded was direct capture from a DVB card so it was an mpeg2 stream. My transcoding option were set to transcode mpeg2 -> mpeg4 Given that mpeg4 is effectively divx I was expecting a good reduction in filesize - instead the file has gone from 2.2 Gb to 2.4 Gb. resulting file is definitely mpeg4 (i checked) .... so the question is can anyone explain the file size increase? D

Author:	ryanpatterson [ Tue Jan 24, 2006 3:48 pm ]
Post subject:	Re: transcoding increases file size ?
declanh wrote: mpeg4 is effectively divx divx is mpeg4 not the other way around. As for your problem, I have no idea. I've never used transcoding myself.

Author:	nickread [ Tue Jan 24, 2006 6:31 pm ]
Post subject:
What are the settings in the default transcoding profile from mpeg2 to mpeg4? Make sure the resolution matches that which you used to record in the first place. And you can vary the bitrate used as well. I transcode my MPEG2 to MPEG4 all the time and it halfs it. Just a thought - are you sure the original file was MPEG2? Maybe it was already transcoded?

Author:	declanh [ Wed Jan 25, 2006 3:01 am ]
Post subject:
nickread wrote: What are the settings in the default transcoding profile from mpeg2 to mpeg4? Make sure the resolution matches that which you used to record in the first place. And you can vary the bitrate used as well. I transcode my MPEG2 to MPEG4 all the time and it halfs it. Just a thought - are you sure the original file was MPEG2? Maybe it was already transcoded? original files are captured from my DVB card - here is what a non transcoded file looks like Video: MPEG2 Video 544x576 (16:9) 25.00fps 10000Kbps Audio: MPEG Audio 48000Hz stereo 192Kbps as reported by media player classic Im using the 'default' transcode settings for mpeg2 -> mpeg4 but im still surprised that the file size goes UP here is the settings for the file i transcoded (according to media player classic) Audio: MPEG Audio Layer 3 48000Hz stereo 128Kbps Video: DIVX 544x576 (4:3) 25.00fps note that the descriptions above are from different files - I did not take note of the film before i transcoded it (it was in 4:3 aspect) still somewhat bemused....

Author:	nickread [ Wed Jan 25, 2006 4:59 am ]
Post subject:
Quote: here is the settings for the file i transcoded (according to media player classic) OK, but what are the settings in the default profile itself (Setup/Recording profiles/transcoders etc)? What bitrate is it using for example? Although must admits its pretty odd...

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Author:	declanh [ Wed Jan 25, 2006 4:33 pm ]
Post subject:
nickread wrote: Quote: here is the settings for the file i transcoded (according to media player classic) OK, but what are the settings in the default profile itself (Setup/Recording profiles/transcoders etc)? What bitrate is it using for example? Although must admits its pretty odd... default bitrate is 2200 kbps which is what its set at should i half that ?

Author:	nickread [ Wed Jan 25, 2006 8:31 pm ]
Post subject:
Alright - so how long (timewise) is the transcoded file? 2.4Gb at 2200kbps should be approx 2 hrs 24 mins or thereabouts (1Gb/hr). If thats the length then the coding is about right. If not, then ?

Author:	declanh [ Thu Jan 26, 2006 1:49 am ]
Post subject:
nickread wrote: Alright - so how long (timewise) is the transcoded file? 2.4Gb at 2200kbps should be approx 2 hrs 24 mins or thereabouts (1Gb/hr). If thats the length then the coding is about right. If not, then ? its 2hrs 11 mins.... suppose thats about right then .. I just expected default settings on transcode to mpeg4 to decrease the filesize ... whats a more sensisble bitrate then is 1100 too low

Author:	nickread [ Thu Jan 26, 2006 2:26 am ]
Post subject:
You can experiment, 2200kbps is what I use. I would question if the original file was MPEG2 at the parameters you say though... MPEG2 480x480, 4Mbps takes about 2GB/hr in my experience, so would have expected your original file to be 5-10GB. Are you sure the original file wasn't already transcoded? Maybe you have autotranscoding turned on?

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