Encoding mpeg2 files??

C2 Digital Studios · Post by **C2 Digital Studios** » Wed May 10, 2006 8:10 pm

Somebody please help my ignorance. If the native file for DVD is mpeg2, then why does Workshop take my mpeg2 files and encode them before rendering??? Thanks.

DVDDoug · Post by **DVDDoug** » Wed May 10, 2006 9:17 pm

If the files are DVD compliant, and if you have not checked the box that says Convert To Disc Template, they should not get re-coded.

You can't use any MPEG-2 file on a DVD. There are restrictions on the resolution and bitrate (and probably other paramaters). For example, Digital Broadcast Video has both a non-compliant resolution and too-high of a bitrate. DigitalFAQ.com has a handy chart showing the allowable DVD formats.

There is a Convert To Disc Template box for both the audio and the video. I'm usually working with non-compliant audio files (or LPCM files that I want to convert to AC3). In that case it has to convert the audio and then re-multiplex the audio and video before burning.

C2 Digital Studios · Post by **C2 Digital Studios** » Mon May 22, 2006 5:39 pm

DVDDoug, I have not checked the the Convert to Disc Template (video or audio), and my mpeg2 files were recorded at 8500kb/sec or roughly 8.3 Mb/sec. Audio was embedded at 48kHz. I believe this fits the suggested encoding specs.

Workshop is still wanting to encode these files.....any thoughts.

Devil · Post by **Devil** » Tue May 23, 2006 11:09 am

1. 8.3 Mb/s is too high for many DVD players, which cannot handle (especially from DVD±R/RW) TOTAL bitrates higher than ~7000 kbit/s or so.

2. MPEG audio uses >1000 kbit/s, so 8500 + 1000++ = >9500, which is too high.

Recommendation: try encoding at 6000 kbit/s CBR with AC-3 audio at 192 kbit/s. You should have no difficulty with that and playback is ensured. The quality will probably be amply sufficient (many Hollywood DVDs are encoded at much lower rates than that).

GeorgeW · Post by **GeorgeW** » Tue May 23, 2006 11:41 am

what are the full attributes of the mpeg2 files in question -- framerate, resolution, type of project you are creating (NTSC or PAL), etc...

Regards,
George

C2 Digital Studios · Post by **C2 Digital Studios** » Tue May 23, 2006 9:03 pm

NTSC 29.97 fps, non drop-frame rate, APPROX., 25 MINUTES, MPEG2 720X480, Video bitrate - 6000kbps (CBR), Audio is 224 Kbps (i've heard 224 should work....i guess i could bump down to 192)

Could the audio set at 224 vs. 192 really be the difference in causing Workshop to re-encode the files??

I'm using the Main Concept MPEG Encoder software. It has a "video encoder quality" setting...I've set it at 47

Devil · Post by **Devil** » Wed May 24, 2006 7:32 am

Whoa! 29.97 fps AND non-drop frame rate. These are contradictory. Non-drop is 30 fps. If your original is 29.97 and your project settings are 30 (or vice versa), then you're going to force re-encoding.

C2 Digital Studios · Post by **C2 Digital Studios** » Thu May 25, 2006 1:40 pm

Which do you suggest?

Devil · Post by **Devil** » Thu May 25, 2006 2:54 pm

29.97 fps, drop frame rate.

deklerkt · Post by **deklerkt** » Tue Jun 20, 2006 11:29 am

Also I noticed that smart rendering only works if you set your project settings at least as high as the highest encoding MPEG file. Otherwise it will re-encode to the lower project standard. Understandable, but you need to be aware of this.

Some other inhibitors for Smart Rendering: it will not happen if the project settings and the MPEG files are:

- different in constant / variable bitrate setting
- project bitrate is lower than MPEG file bitrate
- MPEG files were encoded by different encoders
- different in PAL / NTSC setting

It's logical if you think about it, but better be aware of them beforehand.