Editing AVCHD - What is the correct output setting ?

[GilesM]

All,

I have been having trouble with my IMovie files.
I have a Sony AVCHD Camera and an Imac with an intel Core processor and 4GB of RAM.

When I watch the 'raw' unedited AVCHD files by uploading them to my PS3, they look great, perfect actually.

However, watching unedited footage is not really a good idea, so I import the movies in to I Movie and perform the edits I need.

However, when I export the movies to .MP4 (the PS3 does not play .MOV files), the motion does not look natural, panning shots are juddering and the motion of say a rugby ball in the air is very 'processed' it looks like there is 2 of them !
It's as if all motion is not smooth any more, the whole thing looks very 'processed' and staggered.

The imovie export files are set as:

MPEG-4
Dimension: 640 x 360
Codec : H.264

This is the 'large Movie' option from Imovie.

The original AVCHD files are 1080i high def.

I have Quick Time Pro, and so am not restricted to the output formats available by default in iMovie. These files were made by just selecting 'large movie' and not using the QT Pro.

Can anyone suggest what setting I should be using to make the edited files look just as good as the original source ?
Will upgrading to Final Cut Express help ?
Would using a Mac Mini instead of the PS3 and playing .MOV files help ?

Any suggestions will be gratefully received.

 

[Exman]

You're shooting in 1920x1080i.

You should export the movie to 1280x720i using the AVC codec (H.264).

What you are experiencing sounds like a settings problem, where your source video is interlaced, but you encoded the video progressively.

Set them manually to the resolution I suggested above, however, don't use progressive scan. Your encoded video should remain interlaced (the same as your source). A target bitrate of around 4,00kbs - 5,000kbs will give you very good quality, and a 2-pass variable bitrate (VBR) is best.

There are only two situations where you should encode progressively:

1) The source video is progressive, i.e you shot in progressive scan (i.e 1080p).
2) You de-interlace the source video, i.e remove the fields.

edit: However, AVOID de-interlacing whenever possible. It reduces the picture quality very noticeably.

 

[GilesM]

ex man - thank you

Exman

Thank you for the suggestion. I will try these settings today and get back to you.
I did not realise that the de-interlace would have a negative effect.
I do hope this works, I will be very grateful to you if it does.

I will post back once I have made a few tests.

Thanks again.

 

[GilesM]

Thanks for the advice - my export is running

exman,

So, I have started the export from Imovie project to .MP4 as suggested.
There is only 30 minutes of footage reporting that it will take 144 minutes to make the export.

I guess I will go and watch a movie, then come back to it !.

I do hope this works.
So, perhaps tomorrow I can post back and say how I got on.

Thanks again.

 

[keltorsori]

exman,

So, I have started the export from Imovie project to .MP4 as suggested.
There is only 30 minutes of footage reporting that it will take 144 minutes to make the export.

I guess I will go and watch a movie, then come back to it !.

I do hope this works.
So, perhaps tomorrow I can post back and say how I got on.

Thanks again.

Looking forward to your experience. I've been shooting with an HG20 and have been having a similar problem.

 

[GilesM]

So, I used this alternate export process to make a .MP4 file.
On the iMac it looks good, but unfortunately it will not play on my PS3.
This encode method takes a long time, but the file, when viewed on the iMac does look better, problem now is the PS3 refuses to play it, even though it really should, as it plays other .mp4 files.
Back to the experiments I fear.

In the end I might just replace the PS3 with a mac Mini or even Apple TV, and then I can play the .MOV files without all this messing around.

Does the Mac Mini give good results when used as a media player ?

 

[Exman]

To play MP4 on PS3, you need to encode the audio on the MP4 using the AAC codec, alongside H.264 video codec.

 

[GilesM]

good morning exman

So, I did mess up the encode. Thanks, I guess I can try it again.
I can set it off and just let it run while I am working at my real job

I will give it another go.

thanks again for the info.

 

[Exman]

That's almost another 3 hours of encoding for you, yikes!

Good luck

 

[GilesM]

well, no matter really, my work will keep me busy while it works away.
I am starting to think I might use the 'SD' setting instead of high def from now on.
I filmed a baptism last night for a friend and as they only have SD equipment (i.e an old 'tube' type TV) it did not seem worth it using HD.
It was so much easier to to make a DVD!

You know, I am sure the audio settings on yesterday's encode were right, but I will try again anyway.

I will let you know !

thanks...

 

[mBox]

That's almost another 3 hours of encoding for you, yikes!

Good luck

Any tips on speeding this process up? Besides CPU/RAM? No hardware options out there? Reason Im asking is that Im from the Avid/FCP world. We use mostly XDCAM hard-copied to disk then play, but for home Im thinking of picking up a simple AVCHD camera. Im use to my miniDV real-time acquisition
Any tips would be great!

 

[GilesM]

Well, my exports yesterday failed to play in the PS3. I just can't figure out why.
As far as encoding time, when I started yesterdays encode the estimate was 140 minutes or so. Actual time was just around 60 minutes.

I'm not sure if it helps much, but my iMac has 4GB of RAM.
I does not seem much faster than when I did the same stuff on 1 GB of RAM.
I guess it just takes whatever time it needs, RAM does not seem to be the factor that would speed it up.

 

[Exman]

There is only one more settings I can suggest.

Click on Video Options, chose "Main" and "Single-pass". Your particular PS3 might not like multipass. Single-pass encode will be much faster, but won't produce the same picture quality as multi-pass.

 

[GilesM]

Exman, wow, thank you so much that's great !

I will give it a try this morning. Also, I have found one workflow that works, but is not as good as this as it involves an extra encode. I have taken yesterday's files that was encoded to .MP4 that would not play, and converted it to .MP4 in MPEG Streamclip. This file now works in the PS3.

I guess I could export to Quickitme movie with the res. set to 1280X720.
These .MOV files will be the best for playback on my iMac.
Then convert those to .MP4 using MPEG Streamclip to play back on the PS3.

I prefer your method as it has one less encoding step, which has to be a good thing.

I will try this again this morning. I feel I am getting close to being able to get my hi-Def footage on to my TV at native resolution at last !

Thanks again, I will let you know.

 

[Exman]

The less transcoding, the better. But I am glad you found workaround method with Mpeg streamclip.

I fixed the previous post regarding two identical screenshots.

Good luck again

 

[GilesM]

exman,

Well, that worked. It seems it was the 'multipass' that caused the issue. Thank you very much for your help.

So now I have two files to compare, one that is h.264, MP4 (single pass) and one which is h.264 MP4 (multipass) then converted to a playable .MP4 via MPEG Streamclip.

Now all I have to do is decide which is best (if I can see any difference at all that is).

Thanks again, you have made it work for me !

 

[Exman]

Glad to be of service and even more that it's finally worked out

I am pretty sure a single-pass export from iMovie will give you better quality than a 2-pass-mpeg streamclip conversion. Conversions always introduce artifacts, the less the better

 

[Exman]

Any tips on speeding this process up? Besides CPU/RAM? No hardware options out there? Reason Im asking is that Im from the Avid/FCP world. We use mostly XDCAM hard-copied to disk then play, but for home Im thinking of picking up a simple AVCHD camera. Im use to my miniDV real-time acquisition
Any tips would be great!

Hi mBox,

Video encoding/trascoding is very CPU dependent (and intensive if the application is written well, e.g Adobe Premier). There isn't much you can do if you're limited by hardware.

Having said that, Adobe have something great inline with CS4, which promises GPU acceleration. A GPU is in many ways many times more powerful than a CPU when it comes to mathematical computations, graphics and video work. You might have recently heard that some Russian group have found a way to use a graphics cards to accelerate Wifi password cracking at 100x faster than CPUs can - that's the sort of power a GPU has.

Adobe have said, Premier CS4 can tap into the GPU's power (you need a Quadro at this stage) and accelerate video encoding by 10x (or faster). This sounds quite exciting, but we'll see how it goes in the wild.

The idea of GPU acceleration is not new, it's been around for a while (on the PC). nVidia have enabled GPU acceleration on PC's long ago, it is not a surprise to see an under-powered PCs (more under powered than a Mac mini) able to play full HD contents (1920x1080P) thanx to GPU acceleration. Hardware acceleration is also enabled on AMD chipsets.

It is great to see some form of GPU acceleration finally implemented on OS X. I think Final Cut studio and Avid getting on the act in the not too distant future. Maybe with Snow Leopard.