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View Full Version : Bitrates for converting AVCHD to editable formats?


crashtestwaz
December 31st, 2009, 06:14 AM
Hi folks, I am over the moon to have found this forum. Am eagerly awaiting delivery of a Canon HF200 AVCHD camcorder. I hope to convert the AVCHD footage to something editable with Premiere Elements 4. I want to keep using PE4 because it runs OK on my 'legacy' (i.e. old) Pentium M laptop. I need this because I can edit at work in my lunch time, then encode the video on my quad-core at home. Before finding this forum I had just stumbled onto the Koyote converter.

I am planning to shoot always in the highest quality 1920x1080 setting on the camera. As I understand it, I'll be shooting at 24Mbps (megabits per second). I was thinking that converting to AVI for editing might be best (less re-compression) but am open to advice on this. I want to minimise loss of quality in the converted files - I am not terribly concerned about their size, as I'm already successfully editing large AVI files from MiniDV.

My main question concerns bitrates for the converted videos. I know that AVCHD uses H.264 which is highly compressed. I would think that for a given AVCHD video at 1920x1080, which I want to convert to the same resolution/aspect ratio (1920x1080) in either AVI or MPEG-2, I'd need a significantly higher bitrate. Maybe two, three, four times 24Mbps?

So when converting 24Mbps AVCHD, what AVI bitrate should I use to reproduce the same quality and resolution? What bitrate for MPEG-2? Any suggestions?

Hope I've given enough background - many thanks.

ATR
December 31st, 2009, 09:16 AM
crashtestwaz

I will be back to answer your questions about bitrate, but I believe you have major blocks in your planned workflow.

Premiere Elements 4 does not support AVCHD. Premiere Elements 7 was the first to do so. Premiere Elements 8, the current version, also supports AVCHD. BUT, some Sony Vaio come with Add On which will give AVCHD support to Premiere Elements 4 installed on it. So, what is your computer?

Also, with regard to the computer, AVCHD is very resource demanding. Have you read the thread at the top of this forum regarding editing AVCHD with Premiere Elements?

You may not have neither the software nor computer to edit your AVCHD.

Looking forward to your response on the above.

ATR

crashtestwaz
January 1st, 2010, 07:23 AM
Hi ATR and a happy new year to you.

Sorry if I didn't make myself clear. I am not planning to edit raw AVCHD. Here's the planned workflow:

* Transfer AVCHD footage from SD card to PC (quad-core, 1TB drive);

* Use Koyote HD Converter or similar software to convert AVCHD files into AVI files or MPEG-2 files, i.e. something I can edit in Premiere Elements 4. I am leaning towards AVI files.

* Edit the converted footage (AVI or MPEG-2) in Premiere Elements 4, then encode as necessary into final format.

So what I'm looking for are bitrates for AVI and MPEG-2 for my converted files. I need to find out the bitrates that will give me equivalent picture quality with the same resolution. My AVCHD source files will most likely be 1920x1080, 24Mbps.

Hope I've been clearer this time.

If the above doesn't work out, I might try purchasing PE8 and editing in raw AVCHD using the various software patches and fixes that have been posted here, including the German one (I know there are risks). However this plan rules out using my laptop as a mobile editing station - it is simply too old and creaky for AVCHD.

ATR
January 1st, 2010, 10:32 AM
crashtestwaz

If you are using the Koyote Soft HD Converter, the video bitrate units are "Kbps" (kilobytes per second). Although the program's default appears to be 9000, you can type in a value higher or lower than that.

For his AVCHD 1920 x 1080 conversion to MPEG2 1920 x 1080, cyber wrote that he uses the bitrate of "16384 kb" which would be 16384 kilobytes per second (or 16 megabytes per second aka Mbps). See his AVCHD editing thread at top of forum.

If you are starting with AVCHD with a bitrate of 24 Mbps and you do not crash into file size issues, then try using the Koyote Soft bitrate of 24000 Kbps aka 24 Mbps and maintaining that bitrate in your workflow. If that works great, if not, then experiment with the bitrate to find the compromise between quality and file size for your specific computer environment.

Please update on your progress and let me know if I have targeted your question.

ATR

crashtestwaz
January 1st, 2010, 12:35 PM
Hi ATR, thanks for the advice. Yes, you are targeting my question correctly.

At the 24Mbps setting for AVCHD, I would have expected the AVI version to need a significantly higher bitrate to reproduce the same quality - because AVI is not as aggressively compressed as AVCHD.

Or am I misunderstanding the relationship here between bitrates for different compression schemes?

ATR
January 1st, 2010, 03:44 PM
crashtestwaz

The best thing to do is to do a mini test before the grand projects and see what works in your specific situation (video and computer-wise).

I think that approach is supported by the following link that you might find interesting.

http://www.tmaemarketing.com/blog/2009/03/26/web-videos/quality-a-formula-of-bitrates-and-pixels-part-1-bitrates-compression.html

Cyber's work and bitrate suggestion is a guideline for your MPEG2 1920 x 1080, what worked for him with his video source. But even his suggested MPEG2 bitrate needs keying into your specific situation as does the AVI version.

Please keep us updated on your progress. Could you go into more detail on why you are favoring a converted file with a file extension of .avi, rather than .mpg?

ATR

crashtestwaz
January 7th, 2010, 08:05 AM
Thanks ATR. I have got the camcorder now - just waiting for my 16GB Class 4 SD card to arrive and then I'll start testing.

ATR
January 7th, 2010, 08:35 AM
crashtestwaz

Sounding good.

Am looking forward to your results.

ATR