AVCHD 720p/60 a problem?

Started Feb 18, 2009 | Discussions
LizaWitz Regular Member • Posts: 461
Re: It s not 60 fps !!

stefaan wrote:

Neither do I understand why MOV container is used when AVI or MP4
would be a bit more 'universal' (unless you live in an apple world of
course).

You probably don't know this, but the Quicktime file format, also known as .MOV was licensed to the MPEG consirtium and became the basis for the MPEG4 file format, also known as MP4.

MP4 is a standard, so any operating system can support it. (AVI, however is sorta proprietary and not really standardized.)

MOV H.264 files are OK, but require Quicktime.
Windows does not offer any good out-of-the-box solution (except MS'
own WMV-HD).
AVCHD will/has become consumer standard (for the next few years anyway).
I immediately trancode first to ... mpeg2TS (my low end PC !) to
edit AVCHD.

So, since MP4 and MOV are the same fileformat, you probably see that you don't actually require quicktime. (Though Quicktime is available on windows.) The Windows video libraries will read .MP4 files, and have support for H.264 codecs built in.

This is why I say the MP4 format files with H.264 video is the best choice. For pros, they probably want video that is less compressed than H.264, but for consumers it makes sense.

With MP4 file format and H.264 video, you have a completely standards compliant format and one that any OS can implement support for, and I think every OS already has support for (Windows, Linux and Mac OS X.)

OP muley88 Forum Member • Posts: 51
Re: Wait, what?

Someone said that the ccd will do 30fps max. It that's true, then to supply 60fps in the output file (apparently required by AVCHD 720p/60), either the frames are being duplicated, or the processor is working to take snapshots and looking at frames forward and backward to interpolate and create intermediate (every other) frames between the snapshot frames.

I don't know how h.264 works, but I've read that it's a "motion-compensation-based codec", so that may be happening. In that case, this could be great for video quality because your getting twice the resolution, providing the codec does a good job. It still would be a nice option to forgo that to store twice the video though.

Does anyone know how h.264 works? I've done a bit of reading but not enough, obviously.

stefaan Senior Member • Posts: 1,136
Re: It s not 60 fps !! mp4

Thx Lizawitz.
Very valuable info !!
Now I've had a lot of problems just because of that MOV container.
If I can get it to avi or mp4 the codec is normally not getting me into trouble.
e.g. for the LX3/D-Lux4 M-JPEG MOV files that's exactly what I do... using
mp4cam2avi to do so (witout re-encoding).

In addition, the apple twos sound is not helping at all (and is not understood in windows by default unless using QT or AC3filter).
Would you think H.264-10 in an MP4 container to be future proof ?
--

LizaWitz Regular Member • Posts: 461
Re: It s not 60 fps !! mp4

MPEG-2 as a codec lasted a long time... its still used in HDV and DVDs. H.264 as a codec should last awhile, but it won't last the 15 years that MPEG2 did.

As far as "legs" it will be usable going forward for many years, you might just start capturing to some other format in the future. Codecs are advancing with CPUs and parallelism (eg: multi-cores) so in 5-10 years there will probably be a better codec than H.264.

You'll still be able to use your H.264 footage, you'll probably just start capturing to something else.

But as far as the current state of the art, H.264 is, far and away, the best codec out there. IF you want less compression- for an intermediate format then you might want to use something like Apple Intermediate Codec (or its windows equivielent) but I just used H.264.

My workflow is capture on H.264 (in .MP4 files from my Xacti) import to my editor (Which consists of just copying them to the hard drive, as is.) Editing, and then outputting to H.264 codec MP4 files.

There is only one possible re-encoding, but I think my editor just re-encodes the bits around the cuts and the rest is just copied (unless the size or framerate is changed, of course.)

So, yeah, H.264 is a codec with legs.

stefaan Senior Member • Posts: 1,136
Re: It s not 60 fps !! mp4

Thx again Lizawitz.

BTW, I am quite involved in moviemaking myself, but never really found any 'standard'.

I would be real happy to be able to save in a kind of standard with legs as you put it, like we know in still photography (to some extent anyway).

My workflow was (until now) AVCHD 17 mbps => Mpeg2TS highbitrate 25 mpbs(conversion) 1920x1080 => NLE output MPeg2TS 25 mbps (no re-encoding).

I lose IQ that way, but workflow+result are usable/playable on most lower end systems.
But ... MP4 H.264 high profile without re-encoding ??? How and in what NLE ?

zoranT Contributing Member • Posts: 919
Re: IQ?

so you re saying AVCHD produces worse quality than other possible standards? There are three compression rates offered, as far as I remember, starting with 17MB (or something like that) – I thought the main reason to introduce it was that it uses less memory space, but if it doubles frames to have 60fps that is somehow contradictory....Please clarify for non-experts – will video IQ be better or worse than competitors or previous modells?

LizaWitz Regular Member • Posts: 461
Re: It s not 60 fps !! mp4

stefaan wrote:

But ... MP4 H.264 high profile without re-encoding ??? How and in
what NLE ?

I can only speak for the Mac, and I do my editing in iMovie right now, and just use the files as-is. I think Final Cut Pro also would work this way, but can't say for sure.

Don't know about PC editors....

DirtTrackin52 Regular Member • Posts: 114
Re: IQ?

I was really looking forward to buying this camera...until I read this thread.

OP muley88 Forum Member • Posts: 51
Re: IQ?

Someone correct me if I'm wrong. AVCHD is a container. Inside the container is the video, which is made using the h.264 codec. H.264 is compressing the "raw" video so it can affect quality. Quite a few camcorders and some digital cameras are already using h.264. I'm no expert, but what I've read says that h.264 video retains pretty good quality compared to the original even though it's compressed.

LizaWitz Regular Member • Posts: 461
Re: IQ?

Then you've misunderstood the thread. You should buy this camera, its a fine camera, and all the esoteric details about AVCHD aren't going to amount to a hill of beans when it comes to using the camera.

There's a lot of confusion in this thread, but don't let that stop you from buying what appears to be a perfectly fine camera.

LizaWitz Regular Member • Posts: 461
Re: IQ?

muley88 wrote:

Someone correct me if I'm wrong. AVCHD is a container. Inside the
container is the video, which is made using the h.264 codec. H.264
is compressing the "raw" video so it can affect quality. Quite a few
camcorders and some digital cameras are already using h.264. I'm no
expert, but what I've read says that h.264 video retains pretty good
quality compared to the original even though it's compressed.

You're not wrong.

AVCHD is a format, or a specification. The specification sets a lot of parameters about how AVCHD Files are structured. But the high level view is that an AVCHD file is H.264 vide, and AC-3 Audio in an MPEG2 transport stream.

H.264 video produces MUCH higher quality images for a given bitrate. On just about any HD camera system the bitrate is going to be limited somewhere-- the rate at which data can be written to tape or flash drive, being a common one.

So, the Sanyo Xacti writes out H.264 video in MPEG4 files-- this has advantages I've talked about earlier, but it is still H.264 video at whatever Mbps.

A sony camera might write out H.264 at the same Mbps into AVCHD files.

The quality differences in the video between these two cameras will not be due to compression-- as they are both H.264 at the same bitrate. (Though in real world examples one camera might write it at a higher bitrate.)

OP muley88 Forum Member • Posts: 51
Re: It s not 60 fps !! mp4

Since we're talking about conversion, I've tried taking TZ5 mjpg video in .mov and converting to h.264 using MediaCoder, which seems to be capable but a little hard to figure out. I can do Divx this way, but have failed on h.264.

Anyone have experience with this?

Yem Contributing Member • Posts: 715
Evidence

DirtTrackin52 wrote:

I was really looking forward to buying this camera...until I read
this thread.

Me too (despite the price - £350 on Amazon!). Specifically, this is the only camera out that claims 720p@60. If that's real, it would allow perfectly smooth slow-motion sequences (good for action) which no other camera currently offers.

It'd be nice to have some proof that the camera is or isn't doubling frames. I see no evidence that AVCHD-Lite requires 60 FPS as claimed above.

OP muley88 Forum Member • Posts: 51
Re: Evidence

http://panasonic.net/avc/lumix/compact/zs3_tz7/specifications.html

This link shows Panasonic specs for the camera. From these specs you can see this:

AVCHD Lite (SH: 17 Mbps / H: 13 Mbps L: 9 Mbps):
[NTSC] 60p CCD output is 30p (fps).
[PAL] 50p
CCD output is 25p (fps).

The 60p means 60 frames per second progressive (not interlaced). It looks like Panasonic has chosen 60p and 50p as the frame rates for what they call AVCHD Lite. I see no specs indicating other choices for frame rate. They are also explaining with " CCD output is 30p (fps)" that the CCD doesn't do 60fps, it does 30fps. So there is some creation of two output frames for each one frame from the CCD, and so far we're just guessing as to how this is done. If it is some motion interpolation that creates the extra frames, the video would be really smooth.

My only thought in starting this thread was the processing power it would take to handle 60fps instead of 30fps. At least one person here doesn't think it's an issue. It just depends on your computing power. The other consideration is that if the camera allowed only 30fps output, you could store twice as much video as 60fps and still have acceptable quality for home use. That's not a big deal though because at least you're getting nearly twice the recording time with ACVHD at 60p compared to mjpeg in the TZ5. People have noted that you can convert to a lower frame rate with post processing if you're willing to.

This is probably going to be a great camera. Now that I understand some things better, I'm looking forward to it. It's great to see the h.264 compression, which seems to be spreading amongst the products more now. And the sound should be much better than the TZ5 that I have. Like everyone else, I'm hoping that we see image quality improvements, especially in lower light. That would make an already good camera quite a bit more useful.

Shrapnel Contributing Member • Posts: 787
Re: Evidence

Many thanks LizaWitz for the educational info, I had a gut instinct that AVCHD was just a marketing gimmick and not entirely ideal... thanks for confirming it!

It started as my distaste for clips being spread around different files in a number of folders, rather than being single files... and now I'm even more determined to avoid it

LizaWitz Regular Member • Posts: 461
Re: Evidence

Shrapnel wrote:

Many thanks LizaWitz for the educational info, I had a gut instinct
that AVCHD was just a marketing gimmick and not entirely ideal...
thanks for confirming it!

I have a Sanyo Xacti. I love that camera- its small, and it shoots 720 at 30p, 60p and 1080i. It stores the files as regular MP4 files and so I don't have to import them.

All that being said, I'm seriously considering getting the G1HD when it comes out even though it is AVCHD.

AVCHD really grates on me-- because on the Mac there's not really an editor that will work with the files natively, and importing them into an intermediate codec will result in much bigger files.

But I'll deal with it for the advantages of the G1-- interchangeable lenses, a large sensor for shallow DOF and much more manual control.

I don't know what will get companies to switch from AVCHD, but it alone wouldn't be a reason not to buy a camera, I think.

And I assume I'm probably the person who hates AVCHD the most.

Yem Contributing Member • Posts: 715
Re: Evidence

Thanks very much, that's just what I was after. Pretty compelling.

I can't fathom why they chose to output 60 instead of 30 unless to mislead. It's the "digital zoom" thing all over again. See this extract from a hands on with the ZS3:

"With its full optical zoom range at its disposal, the ZS3 shoots 720p HD video at a super-smooth 60 fps (and with stereo audio capture to boot)."

Personally I'll be weighing up this vs a Canon 960IS or SX200.

LizaWitz Regular Member • Posts: 461
Re: Evidence

Yem wrote:

Thanks very much, that's just what I was after. Pretty compelling.

I can't fathom why they chose to output 60 instead of 30 unless to
mislead. It's the "digital zoom" thing all over again. See this
extract from a hands on with the ZS3:

"With its full optical zoom range at its disposal, the ZS3 shoots
720p HD video at a super-smooth 60 fps (and with stereo audio capture
to boot)."

Personally I'll be weighing up this vs a Canon 960IS or SX200.

Where's the misleading? 60p is smoother than 30p. I've been choosing 720p at 60 on my camcorder over 30 and 1080i because the image quality is nice.

mpgxsvcd Veteran Member • Posts: 8,094
Re: Evidence

What camcorder currently shoots at 60 FPS progressive?

LizaWitz wrote:

Yem wrote:

Thanks very much, that's just what I was after. Pretty compelling.

I can't fathom why they chose to output 60 instead of 30 unless to
mislead. It's the "digital zoom" thing all over again. See this
extract from a hands on with the ZS3:

"With its full optical zoom range at its disposal, the ZS3 shoots
720p HD video at a super-smooth 60 fps (and with stereo audio capture
to boot)."

Personally I'll be weighing up this vs a Canon 960IS or SX200.

Where's the misleading? 60p is smoother than 30p. I've been
choosing 720p at 60 on my camcorder over 30 and 1080i because the
image quality is nice.

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MrClick Senior Member • Posts: 1,886
AVCHD vs. MPEG2 vs. MP4 and MOV

nt

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