Difference between Muxing and Transcoding?

jaybee

jaybee

jaybee

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I've confused myself. What is the difference between:

Encoding
Re-encoding
Decoding

Muxing
De-muxing

Transcoding

I use PS3 Media server and I have been using my powerful main rig to do so over ethernet to avoid any problems. Now I'm not so sure I have it set up right, as I have been reading that people find with the majority of mkv files they have, "ONLY" a Mux is required for the PS3 to play it which is very much less intensive than a full transcode.

My poor mans method of understanding it was as follows:

PS3 can't play .mkv files natively and as a result we use PS3 media server so that the mkv file gets transcoded on the fly to a readable format (MPEG?) for the PS3 to play it which requires a fairly capable CPU for full 1080p high bit rate rips. Is this not the case? What is the difference between muxing and transcoding and how do you know which one PS3MS is doing?

Reason I ask, is that if all of mkv files are "JUST" being muxed, this may mean that I can use a low powered file server to perform the same task ? ?


Argh! help
 
I believe;

Encoding - Compressing video, generally using a more efficient codec ie from raw video to MPEG2
Re-encoding - Doing the above again, ie from MPEG2 to h264
Decoding - Interpreting the codec

Muxing - Putting video/audio/subtitles etc into a container
De-muxing - Taking the above out of a container

Transcoding - Encoding on the fly
 
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If your mkv's contain audio and video streams that are understood by the ps3 then demuxing from mkv and re-muxing into another container (mp4?) is required for the ps3 to decode (this is fast). If the mkv contains audio and video that the ps3 does not understand then they need to be either transcoded, or demuxed, and then re-encoded into a different format, and then remuxed into a suitable container (this is slow).

If you are worried about needing a powerful machine to transcode then you could re-encode the mkv's (the ones that need it) on the powerful machine as a one off job and then they are in the right format for the ps3 whenever you need them.

jellybeard999 is correct with the above - although i guess technically decoding isnt anything to do with displaying the video but thats nitpicking.

EDIT - if im gonna nitpick then id better be pretty close to the fact myself!
 
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PS3 media server can either transcode using MEncoder or use tsMuxer to remux on the fly if the PS3 can read the audio and video formats within the mkv.

Incidentally if you make MEncoder downscale the video i.e. 1080p->720p before encoding it uses less CPU, my old dual core C2D can't transcode 1080p but can do 1080p->720p then transcode.
 
What core2duo was that? I have read of many people saying that "any core2duo" should be ok for 1080p transcodes via PS3MS. I also found like yourself that this is not the case. I had a poverty spec old e2140 which is core2duo equivalent power, and even overclocked 100% it still couldn't do it.
 
Transcoding is just converting from one digital format to another whether it's done in realtime or not. It's the same as converting an MP3 file to WMA for example.
 
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You could also run MK2VOB on the files before-hand and then save on trancoding on the fly....
 
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Rozzy85 said:
Transcoding is just converting from one digital format to another whether it's done in realtime or not. It's the same as converting an MP3 file to WMA for example.
Click to expand...

So why do people say sometimes you can get away with just muxing and how do you define that? Because the PS3 cannot read mkv files natively. Sigh...I still don't think I get it. lol < thick
 
jaybee said:
So why do people say sometimes you can get away with just muxing and how do you define that? Because the PS3 cannot read mkv files natively. Sigh...I still don't think I get it. lol < thick
Click to expand...

If the MKV is encoded in H.264 (Which most of them are) - then the PS3 can just get away with converting the Audio (as the PS3 can only deal with AC3 I believe)
 
This might explain it better:


mkv2vob: New App to Remux MKV x264/AC3 which play on PS3

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I have created a program which will remux mkv with x264 video and AC3 audio to a vob file which is playable on the sony ps3.
No transcoding/recompression is done, the streams are simply split and mux into the vob.
Previously there was no way to get AC3 audio on the ps3, only AAC stereo.



.....from doom9 forums
 
Muxing means taking multiple signals or data streams and combining them into one signal/file. The data isn't converted in anyway. I'd imagen the data streams are demuxed from the MKV and the data streams feed to the PS3 which it can decode. The stream data inside is probably MPEG-4/AAC or something common that the PS3 can understand.
 
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