FCP, HDV, and H.264
 

Though I’ve had a couple of years experience editing DV in Final Cut Pro, I wasn’t altogether prepared for the extensive time needed to transcode 1080i60 HDV projects to the H.264 codec—despite warnings contained in some of the threads which I had read at DV Info.net. I had figured on an increase in time by at least a factor of six, given the corresponding difference in pixel counts between DV and 1080 HDV. So when I purchased an XL-H1 from TapeWorks Texas a couple of weeks ago, I jumped right into videotaping a local lecture that lasted about an hour and a quarter, and commenced to cutting/ rendering/ transcoding it via Final Cut Pro on a dual processor 2.5 Ghz G5. I captured the file from the XL-H1 into the Apple Intermediate Codec, and dropped it into an AIC sequence. Just to make things interesting I added a handful of titles with Motion, punched up the brightness of the clip a bit, and kicked in the “Broadcast Safe” filter to clamp the brightest whites. But after sending the sequence directly to Compressor from FCP in order to generate an H.264 file, I was hit with sobering news from the Batch Monitor that it would take around 700 (seven hundred) hours to process this 75-minute sequence! Not possible, I thought; I must be doing something terribly wrong. To make a very long story short, after numerous aborted tries and bouts of self-doubt (e.g. Compressor seemed to restart itself again and again, leading me to the erroneous belief that it was stuck in a loop), I stripped a simple five-minute section of the clip of all filters and proceeded to document the transcoding progress in order to superficially understand how Compressor generated H.264 files. I’d like to now share that experience with DV Info readers and hopefully learn from others what experiences they’ve had with H.264 while working with FCP as well as with other platforms.

First of all, on the dual processor 2.5 Ghz G5 it took Compressor 6 hours and 15 minutes to transcode a 5-minute clip from an AIC timeline to H.264: a 75/1 ratio! What I discovered, however, was that Compressor, with its stock setting for producing a 60-minute H.264 movie, required four passes to achieve its goal. At 30 frames/second, five minutes yields 9,000 frames. The first pass took about 1 hour 20 minutes, processing an average of about 112 frames/min. The second took 1 hr 47 minutes, at a rate of about 80 frames/min. The third was similar to the second: about 1 hr 46 minutes at 85 frames/min. Finally, the fourth pass was similar to the first, taking about 1 hour 22 minutes at about 109 frames/min. The final pass was also the most interesting for two reasons: it produced the widest variation in frames/min (from around 111 to 128 at any given moment), and around every 28 frames the frame count would flash the term “audio.”

Six hours and 15 minutes is one hell of a long time to transcode a 5-minute clip. But what is really maddening about FCP 5 is that the H.264 setting gives offers a “time left to process” and percentage-of-work-completed numbers that bear little resemblance to the real figures at any given time—except at the finish line. Shortly after the beginning of the first pass, Compressor indicated that 14 hrs 10 minutes remained. At the beginning of the second pass an hour and 20 minutes later, the indication was that about 12 hours remained, and that Compressor had completed 10% of the job. One hour 40 minutes later, at the beginning of the third pass, 11 hours 16 minutes officially remained, with 21% of the work completed. At the start of the fourth pass, at about an hour 46 minutes later, around 10 hours were purportedly left, and 40% of the job done. Thereafter, the times rapidly fell to zero and the percentages rapidly increased to 100%, offering a welcomed sense of relief. The movie looks great.

Now, it is possible to create a custom setting in Compressor based on its 60-minute H.264 default setting, and then to uncheck the multi-pass box to significantly reduce transcoding times. I haven’t yet done this to compare the quality between one-pass and multi-pass H.264 movies, however, so don’t know yet what I might find.

Based on my experience with the 5-minute clip, I figure that my entire 1 hour, 15 minute sequence will take four non-stop days to transcode. To lose the services of my fastest computer for this long will require a juggling of projects—perhaps even a short vacation on my part. I’m definitely looking forward to FCP 6 in hopes of some speed improvement, praying for a quad-processor Macintel desktop machine to show up soon in the marketplace, but am also most interested to learn how many forum people are using, for example, Sorenson Squeeze on existing Macs to generate H.264 files, or how other platforms are generally behaving vis-à-vis H.264. It is also possible, of course, that there is something egregiously wrong with my workflow, in which case I’d be happy to hear what others have to say about that.

Can't contribute much here - haven't encoded much in h.264. Out of curiosity: what frame size did you transcode to? To speed-up Compressor jobs, I can highly recommend using Qmaster if you have a few other Macs in your arsenal. I'm curious to find out how single-pass transcoding will compare to your original findings...

First of all, GREAT POST. Thanks for sharing your experience.

Second, like Ron said, look into Apple Qmaster (comes with DVD SP, SHAKE and FSC) and use every available Mac you can muster up. I've toyed around with it a bit, and while it's not a direct linear speed increase, it definately DOES speed things up. I've attached a couple of Mac Minis just as a test and it works pretty well. I wish I would have run formal 'tests' to give you benchmarks, but I didn't have that kind of forethought. :-(

http://www.apple.com/support/qmaster/

H.264
 

I don't think that there is anything wrong with your system. In fact, I'm jealous at the speed with which you can get your encoding done. I have native HDV projects that have taken anywhere from five to ten hours per minute to render to 1280x720.
That's right. Ten hours per minute! (G5, Dual 2.5, 4GB, latest FCP Studio)

I am also surprised that there has not been more of an uproar over this. I suppose that there will be some kind of incredibly expensive hardware solution coming. Just wait for me to buy it and six weeks later it will be a fraction of the price.

Looks great though, doesn't it?

Just did some test of my own.

The footage was 1280x720/30p captured using AIC.

I rendered a 78 minute timeline and it averaged out to 30 min per 1 minute of footage using the H.264 "90 minute" preset which is 6.75Mbps.

I then rendered a 1 minute timeline using the "60 minute" H.264 preset which is 10.3Mbps and it only took 20 minutes.

I guess the 60 minute preset is faster probably due to less compression.

I am using an Intel Imac DuoCore 2.0Ghz

For what it's worth, I'm currently using Canopus Edius on a modest dual-core PC and can render to Windows Media at 1280x720 resolution at a rate of about 6-8 minutes per minute of timeline, using single-pass encoding. Even that seems slow to me for something like a 90 minute wedding video, so I'm definitely interested in more time-effective solutions. For now it appears the quickest thing to do will be to render back to MPEG2-TS, which is reportedly near real time with the Canopus "Speed Encoder" on sufficiently powerful computers - and no doubt with other similar tools as they become available.

I figure a single-layer Blu-ray disc will hold over two hours of 1080i video at a data rate of 25 Mbps, which corresponds to the quality level of my HDV source. So if Blu-ray becomes commonplace and I can encode output for that in real time which looks acceptable on typical HDTVs, that's a workflow which makes sense to me. If you really want H.264 output and want the best possible quality using two-pass encoding and all that then you may be stuck waiting for long renders, but it's good to know there will be other options when rendering time is a significant consideration. We should also soon start to see real-time H.264 encoders using single-pass encoding, so if the quality of those is acceptable that could also be worth considering.

Ernest,

You should try exporting your sequence as a quicktime movie and DO NOT CHECK "self-contained" or "recompress." This doesn't take long at all because it creates a QT movie with markers to the original source AIC files on your hard drive.

Now close FCP and restart (to free up all available RAM) and only open compressor. Drag your QT file in, apply the H264 codec, and do the same test. I think you will find that there is a drastic speed increse over extracting each frame directly from the FCP timeline.

I'm hoping to buy 4 or 5 mac minis to use as a small render/compressing farm. Check the qmaster link above.

I'm going to try that next time I have a few days off!

Is it really that much faster? I normally export to compressor directly off the FCP timeline.

OK guys, I just finished my final test.

I created a "non-self contained" quicktime reference movie off the FCP timeline, this only took a few minutes and took less than 1 GB of hard disk space. I then shut down FCP and opened compressor where I imported the quicktime movie. I used the "60 minute 10.3Mbps H.264" preset this time.

Great results! For a 78min timeline, Compressor averaged 22 minutes per 1 minute of footage.

My conclusion, I would highly recommend this workflow. Don't use the "90 minute 6.75Mbps H.264" preset. It averaged 30 minutes per 1 minute of footage and through comparison tests, the 60 minute preset was of slightly higher quality w/ fewer compression artifacts. Just make sure you have a DL burner because the file is 7GB.

I'm so excited about this! I've already burned an HD DVD w/ DVD studio pro.
These disks are suppose to work on HD-DVD & Blu-Ray disk players, so I'm all set to deliver HD to my clients.

Facts:
Footage was 1280x720/30p originally captured via AIC codec from a JVC HD-100. Computer in an Imac Intel CoreDuo 2.0Ghz

Really Dumb Question
 

Hi Guys,

Ernest, great info, thanks for taking the time.

Why are you not using the AIC as your master?

Why do you go to the H.264?

I'm about to start principal on a feature with the JVC HD100 and had thought I would use the AIC as my finished master.

Any info would be appreciated.

Thanks,

Tom

www.tomchaney.com

2 reasons. First off, you need to use a format that is compatible with DVD players. For standard definition DVD's, you will use MPEG-2 compression. For High Defintion DVD's you will use H.264.

Secondly, the data needs to be heavily compressed at a 10:1 ratio. This allows you to fit that 80min/45GB timeline onto an 8GB DL DVD.

You have to do it this way if you want to author a real DVD or HD-DVD.

Thanks Scott,

What happens when the Blue Rays become a part of our lives?

They will hold much more data, do we still need the H.264?

Tom

We won't have to compress the file so much which means faster encode times.

Remember that when you go directly from FCP's Timeline window to Compressor, Compressor ignores all your render files and the whole Sequence gets re-rendered from scratch. Has to do with image quality some how.

Also, exporting to a Self Contained QT movie will cut your time down quite a bit. Don't check the Recompress Frames box, but do check the Make Self Contained. That's very important for the time issue.