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Converting MPEG4 to AVC
I imported a lot of AVC files 1920x1080P but then mistakenly rendered the project out as MPEG4 with the same settings. I say mistakenly because I wish to put the project onto a Blu-ray disc & as I understand it DVDA will only accept without re rendering interlaced footage. Please correct be if I am wrong about this?
I would be interesting to know if the MPEG4 files was imported back into Vegas & re rendered out again with the 2 separate streams would this result in a quality loss?
Thanks in advance
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9 Replies
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What do you mean by MPEG4? MPEG4 can mean a lot of things. ASP, Sstp, AVC/H.264.
What “render as” encoder did you use?
Did you mean MP4? MP4 is just a generic file container. Sony AVC and Mainconcept AVC can both output MP4 files and of course they contain AVC video. XDCAM EX outputs MP4 files but contain MPEG-2 video streams.
The only other thing in Vegas that can be considered MPEG-4 is the HDCAM SR encoders. This is MPEG-4 SStp protocol.
AVC is acceptable for Blu-ray.
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[Paul Gregory] “I would be interesting to know if the MPEG4 files was imported back into Vegas & re rendered out again with the 2 separate streams would this result in a quality loss?”
Yes, Any time “rendering” is involved, quality is lost. You should render them to the correct format in the first place. Use either Sony AVC or MainConcept AVC with one of the “Blu-ray …” templates. Then render your audio stream as Dolby Digital AC-3 and give it the same name. DVD Architect will then know that the video .avc and audio .ac3 are a single movie.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
I can’t recall exactly just what template I had used to create the MPEG4 file I do recall that it said that it was 1920 x 1080. I thought that I had ticked the box to automatically make output match input but apparently not.
I also thought that possible a MPEG4 file could display at exactly the same quality as the AVC one used by DVDA,& if this was the case maybe it might be possible to deinterlace the file before reassembling it by the Blue-ray player.
It’s such a pity that the electronic companies didn’t have enough for sight,when TV went digital to just get rid of all the different systems pal/ntsc, different frame works etc & just have one universal standard for all digital TV. I just suppose that life wasn’t meant to get this easy because it would allow less manipulation & control by big business.
Thanks in advance
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[Paul Gregory] “It’s such a pity that the electronic companies didn’t have enough for sight,when TV went digital to just get rid of all the different systems pal/ntsc, different frame works etc & just have one universal standard for all digital TV.”
Well they did standardize on the resolution so all HD is either 1920×1080 or 1280×720 regardless if it’s NTSC or PAL. The reason NTSC and PAL have different frame rates is because electric current in the US is 60 Hz and in Europe it’s 50 Hz and frame rates are a multiple of the current so that would be much harder to fix.
I do agree that digital TV should have done away with interlacing once any for all. Too bad they didn’t.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
A friend also told me about another video thing that needs fixing. He likes to record free to air TV onto his PC so that he can chop out the adds & then convert the original,(MPE2 or TS stream I think) to the much smaller H264 file in an MKV container. His problem is that he wishes to keep the subtitles. It seems that the various programs that are used to do this requires him to extract & save the original subtitles from the program that does the editing & then put back the same titles into the program that’s doing the recode. You would think that this should all be automated.
Thanks in advance
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For us to help we really need to know what you did. Otherwise we are feeling our way through the dark. In the case of “render as”, what encoding template did you use.
For “render as”, there really is no match input option. You choose what you want and Vegas does what it needs to do to comply to that request.
If your source is 1080 and 30fps progressive or 60i interlaced then you would choose the 1920×1080-60i template. The Sony AVC encoder gives you a couple of bitrate choices. 10 and 16Mbps. Mainconcept AVC gives you a 25Mbps choice. If you want a higher bitrate you can increase that and save a custom template if you like.
At 1080, Blu-ray officially supports 23.976, 24.0, and 50i and 60i modes.
https://forum.doom9.org/showthread.php?t=154533 -
Thanks for the effort to reply to my question. It will be quicker & easier just for me to re render the file out again since I still have the veg file. As I said in the original, my question was mainly that of trying to understand how everything works and finding out it a render would result in quality loss.
Thanks in advance
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[Paul Gregory] “and finding out it a render would result in quality loss”
Since we are encoding with lossy compression algorithms, the answer is there is always loss. How much, well then we are talking about specifics. What we care about is what we can see and not mathematical loss.
If you render out at the same bitrate as your source at the same codec, say AVC, then you really should not see any loss. If you render at half the bitrate of your source, then you may, or likely, will see issues in places. There no 100% answer to this other than render a sample and watch it.
Cameras do not do much if any inter-frame compression. They do not have the time or the power to do so. When we encode on our PCs, we do get this where possible. I mention this because it is very possible for you to render on your PC at a much lower bitrate, in the same codec like AVC, than a camera source and still get the same visual quality.
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[Paul Gregory] ” It will be quicker & easier just for me to re render the file out again since I still have the veg file.”
I agree. It’s always better to do it right the first time.
[Paul Gregory] ” As I said in the original, my question was mainly that of trying to understand how everything works and finding out it a render would result in quality loss.”
Stick to the Blu-ray templates if you plan to deliver on Blu-ray and you can’t go wrong. Re-rendering is always lossy with MPEG4. If you have multiple delivery targets, render multiple times to each different target.
~jr
http://www.johnrofrano.com
http://www.vasst.com
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