MPEG2 versus H.264??

[Desmond Sukotjo]

I've read somewhere in Adobe's site. It is said that H.264 can actually produce the same quality as MPEG2 but with half data rate. And I've read somewhere else saying that MPEG2 can produce 2 hours HD project for single Blu-ray disc, while H.264 can produce 4 hours. If this is the case why don't we all just use H.264 and drop MPEG2 for all our HD Blu-ray projects??
Any comments??

Thanks in advance.

[Brian Boyko]

Originally Posted by Desmond Sukotjo

I've read somewhere in Adobe's site. It is said that H.264 can actually produce the same quality as MPEG2 but with half data rate. And I've read somewhere else saying that MPEG2 can produce 2 hours HD project for single Blu-ray disc, while H.264 can produce 4 hours. If this is the case why don't we all just use H.264 and drop MPEG2 for all our HD Blu-ray projects??
Any comments??

Thanks in advance.

H.264 is great, but it requires a heck of alot more processing power than MPEG-2. So, yes, you could encode everything as H.264 and improve workflow that way - if you've got a week of 24-hour days to let your movie render.

[Kevin Shaw]

Originally Posted by Desmond Sukotjo

If this is the case why don't we all just use H.264 and drop MPEG2 for all our HD Blu-ray projects??

Because H.264 can take up to ten times longer to render for about the same level of output quality, and is harder to re-edit later if you encounter a need to do that. One of the good things about Blu-ray is that you can fit over two hours of content at full HDV quality on a single-layer disc...if you need more time than that then go ahead and use H.264 (or use a dual-layer disc).

[Desmond Sukotjo]

Can I combine the two into the same blu-ray disc for authoring?
Some tracks MPEG2 and others H.264.

[Kevin Shaw]

Originally Posted by Desmond Sukotjo

Can I combine the two into the same blu-ray disc for authoring? Some tracks MPEG2 and others H.264.

I think that's supposed to work, but it's something you'd want to test yourself before counting on it.

[David Moody]

I have been testing some of my FX1 footage (edited with a Cineform intermediate), and have not been as happy with the MPEG2

I also think that 2 hours for MPEG2 and 4 hours for H.264 is generous.

A single sided BD-R is 25GB, which is the same as your 1 hour HDV tape recorded in MPEG2. To get two hours you would have to halve the data rate of your original source.

Blu-ray movies that come out on 25GB discs with MPEG2 are not considered reference quality.

It may be overkill, but I am using H.264 with under two hours of length so that I don't have to use the lower quality setting in Encore CS3.

[Kevin Shaw]

Originally Posted by David Moody

A single sided BD-R is 25GB, which is the same as your 1 hour HDV tape recorded in MPEG2. To get two hours you would have to halve the data rate of your original source.

Nope, 25GB is more than enough for two hours of 1080i HDV at full 25 Mbps bandwidth, which is consistent with the fact that an hour of DV or HDV footage uses about 12 GB of storage when captured to a computer. You can also calculate this directly by figuring that 25 Mbps = 3.125 MB/sec plus another 48 KB/sec for audio, or ~11,423 MB per hour of HDV.

Blu-ray movies that come out on 25GB discs with MPEG2 are not considered reference quality.

Any quality concerns about early Blu-ray movies were likely the result of using low bit rates to pack more content on the discs, which makes sense for a full-length movie plus extras based on the above calculations. I made my first Blu-ray disc recently using the default settings in Adobe CS3 and it looks great, even though Adobe compressed it to MPEG2 with a bit rate varying from ~10-15 Mbps. (Which is irritating because it was a short test project that could have been encoded at a higher bit rate.) Long story short, MPEG2 at 25 Mbps should look as good as anything you get from a broadcast HDTV signal or an H.264 file at a lower data rate (say ~10-12 Mbps).

[David Moody]

I may be confused, but I thought that HDV 1080i was 25 mb/sec.

I seemed to get some stuttering with MPEG2 on some time lapse footage that I did not get with h.264, so I switched to h.264

For three hours of footage with h.264 I have to go to lower than standard settings with Encore, and I seem to notice a difference in compression artifact.

It takes a while to test different encode rates when the render is 48 hours, so I am still experimenting.

[Kevin Shaw]

Originally Posted by David Moody

I may be confused, but I thought that HDV 1080i was 25 mb/sec.

It is, but remember that's shorthand for 25 megaBITS per second, which you have to divide by 8 to get the date rate in megaBYTES per second. (Because one byte = 8 bits.) So 25 Mbps = 3.125 MB/sec, or 11.25 GB/hour (plus audio).

Regarding your test renders, try running them on a short (e.g. 1 minute) clip for testing purposes, so you don't have to wait 48 hours for the results. :-)

[Desmond Sukotjo]

[QUOTE=Kevin Shaw;756385]25GB is more than enough for two hours of 1080i HDV at full 25 Mbps bandwidth, which is consistent with the fact that an hour of DV or HDV footage uses about 12 GB of storage when captured to a computer. You can also calculate this directly by figuring that 25 Mbps = 3.125 MB/sec plus another 48 KB/sec for audio, or ~11,423 MB per hour of HDV. [QUOTE]

Kevin. How does this calculation applies to H.264?
I looked up in premiere media encoder.

MPEG2 Blu-ray - HDTV 1080p 25 High Quality
Target Bitrate 30Mbps

H.264 Blu-ray - HDTV 1080p 25 High Quality
Target Bitrate 25Mbps.

So what I don't understand how can H.264 fit 4 hours of video on blu-ray disc. If we use your calculation above, we can only fit about 2 hours of video either using MPEG2 and H.264 compression.


Thanks Kevin.

[Kevin Shaw]

Originally Posted by Desmond Sukotjo

How does this calculation applies to H.264? I looked up in premiere media encoder.

MPEG2 Blu-ray - HDTV 1080p 25 High Quality
Target Bitrate 30Mbps

H.264 Blu-ray - HDTV 1080p 25 High Quality
Target Bitrate 25Mbps.

So what I don't understand how can H.264 fit 4 hours of video on blu-ray disc. If we use your calculation above, we can only fit about 2 hours of video either using MPEG2 and H.264 compression.

Based on the settings you described you couldn't fit any more content using H.264, but the whole point of that format is you can get equivalent quality at a lower bit rate. So change the target bit rate for H.264 to something like 12 Mbps and you should get decent output quality with twice the capacity compared to MPEG2-HD at 25 Mbps. The advantage of using MPEG2 is that it's MUCH faster to encode than H.264 at HD resolutions.

[Desmond Sukotjo]

I got you Kevin. Thanks. It all make sense now.