Exporting AVCHD to HD MPEG2

[Ted]

In another thread, Paul LS wrote:

"Alternatively to avoid the frustration you could export the clips from PE7 as HD MPEG2 and bring these back into the project and edit them. PE7 handles HD MPEG2 clips much better then AVCHD. Alternatively if your final export is standard definition convert to DV-AVI and edit these."

How does one go about doing that in PE 7?

Thank you!

[alaskamovieguy]

From PE7 place all your clips on the timeline, save, then Share/Personal Computor/select the Mpeg2 1080 preset or the DV-AVi depending on if your final project will be HD or standard DVD. It will transcode the avchd files into whichever of the 2 you selected and then you can bring the resulting file back into PE7 for a smoother editing. As you already know it will take some time for the transcoding. The DV-AVI file will be very large.

[Ted]

From PE7 place all your clips on the timeline, save, then Share/Personal Computor/select the Mpeg2 1080 preset or the DV-AVi depending on if your final project will be HD or standard DVD. It will transcode the avchd files into whichever of the 2 you selected and then you can bring the resulting file back into PE7 for a smoother editing. As you already know it will take some time for the transcoding. The DV-AVI file will be very large.

Thanks for taking the time to answer, AK! Very much appreciated.

Is this the workflow you use? When you say "smoother editing", what do you mean? I guess I'm wondering what the advantages are of doing this rather than just working with the native AVCHD data.

Again, thanks!

[alaskamovieguy]

By smoother editing I mean your processor can better keep up with the large amount of data inherent to HD. The Mpeg2 isn't nearly as compressed as the avchd and the DV-AVI isn't compressed at all, rendering the avchd files in the time line instead of doing the transcoding will serve the same purpose to a large degree. Just various ways of trying to accomplish the same thing. Which works best for you depends on your hardware capabilities, your needs etc. Most of my editing doesn't really require taking the time to do that, I am usually just trimming the ends of the clip and not doing any real creative editing that requires smooth playback. If you do the Mpeg2 1080 transcodeing and then import the file back into PE7 for editing, add transitions etc. and then export again or burn to disc etc then you will be transcoding a second time which will cause some degradation but minimal, just so your aware.

[Ted]

Great, thanks, AK! That makes sense... I just need to play around with it.

[ChancyRat]

I'm too inexperienced to understand most of this. Don't you lose HD quality when you convert ACHD to mp2? I have thought only converting to 264 1920 x 1080, producing an .mts file (then manually changing the dot extension to .mp4) would produce the highest quality HD.

Or, are you saying convert to mp2 and then when you're done, convert to mts?

[Paul LS]

The HDV MPEG2 standard stipulates a bit rate of 25Mb/s and the quality is the same as AVCHD at a bit rate of 16-18Mb/s (about what AVCHD camcorders produce)... so the quality is about the same. it is just that AVCHD is more highly compressed and so you can get the same quality at a lower file size with AVCHD.

However as AVCHD is more compressed it requires a lot of processor power to edit it smoothly... as HDV MPEG2 is less compressed it takes less processor power.

[ChancyRat]

The HDV MPEG2 standard stipulates a bit rate of 25Mb/s and the quality is the same as AVCHD at a bit rate of 16-18Mb/s (about what AVCHD camcorders produce)... so the quality is about the same. it is just that AVCHD is more highly compressed and so you can get the same quality at a lower file size with AVCHD.

However as AVCHD is more compressed it requires a lot of processor power to edit it smoothly... as HDV MPEG2 is less compressed it takes less processor power.

I'm editing on a really unacceptable machine - 2 GB RAM, Core Duo, 2.49 GHz, with currently about 40 GB space free. From what you say, it appears that MPEG2 draws less on the GHz, but more on the RAM?

And do I understand this also, that a 5 minute AVCHD file as mp4 will be smaller in size than a 5 minute AVCHD file as MPEG2?

If one needs the file to be smallest possible in size, but as excellent HD, and with an inadequate machine, what would you recommend?

Thinking the mysteries of the universe may soon be solved...

[Ted]

Thanking all the contributors because I'm learning a great deal from this thread!

[Paul LS]

HDV MPEG2 file sizes are larger than AVCHD so they use more harddrive space... the RAM requirements is the same. Infact HDV MPEG2 has the same file size as standard definition DV-AVI about 13GB per hour whereas AVCHD runs at about 8GB per hour.

Regarding your MP4/MPEG2 comparsion. yes, an AVCHD video converted to MP4 would have a smaller file size than an AVCHD converted to MPEG2 as MP4 is more highly compressed.

So for editing, for the smallest file size at HD quality you would go with AVCHD... but if you have an underpowered machine for AVCHD editing then it would be better to go with HDV MPEG2. The harddrive storage requirements are approximately 40% more for HDV MPEG2.

[ChancyRat]

HDV MPEG2 file sizes are larger than AVCHD so they use more harddrive space... the RAM requirements is the same. Infact HDV MPEG2 has the same file size as standard definition DV-AVI about 13GB per hour whereas AVCHD runs at about 8GB per hour.

Regarding your MP4/MPEG2 comparsion. yes, an AVCHD video converted to MP4 would have a smaller file size than an AVCHD converted to MPEG2 as MP4 is more highly compressed.

So for editing, for the smallest file size at HD quality you would go with AVCHD... but if you have an underpowered machine for AVCHD editing then it would be better to go with HDV MPEG2. The harddrive storage requirements are approximately 40% more for HDV MPEG2.

You are a knower of all things important.
Is the size of the MP4 significantly smaller than an MPEG2? Is there a known percentage? If it is 1% smaller, perhaps I could stand to loose the size savings in favor of faster editing. If it is 15% smaller ...
And - does the type of editing matter? Straight clips versus 30 clips and 20 titles? Does that affect the percentage size difference?

Speaking of size matters... If I have two videos, each has exactly the same clip and title, but in one the title is just text, and in the other the title is text + animation, is there a known size difference in those two? Or, maybe a better example, same clip but one has title + color matte, the other only title? A friend said probably not, because if the title still runs 10 seconds in both, that's what determines the size. I said that can't be, the addition of the animation clip would add to size.

In the spirit of hanging on to a functioning machine and small size...

[Paul LS]

MP4 is smaller than MPEG2 but it is difficult to say how much smaller the file size would be. It depends on which tyoe of MP4 codec you use (there are many) and it depends on the compression setting. But I think you could assume that at the same quality an MP4 file size you be 60% of the MPEG2 file size.

That said, if when you are editing you render a clip by hitting the Enter key on your keyboard... for example to get the video to play back smoothly or to see an applied effect, PE7 will generate a temporary "render file" that replaces the video on your timeline and this file will remain on your computer until you delete it. This "render file" is an MPEG2 file. So... if you edit MPEG2 you may not need to render portions of your timeline and so you will not generate these MPEG2 render files. Whereas if you edit AVCHD/MP4 you will probably need to render your timeline thus generating large MPEG2 files.

If you are really restricted on harddrive space to the extend that you are concerned about the extra size that an animated title might add then I think you are going to be in for trouble , as when you export your timeline it will be rendered.. and this rendered file will be MPEG2. May be time to buy an external USB hard drive!

[ChancyRat]

MP4 is smaller than MPEG2 but it is difficult to say how much smaller the file size would be. It depends on which tyoe of MP4 codec you use (there are many) and it depends on the compression setting. But I think you could assume that at the same quality an MP4 file size you be 60% of the MPEG2 file size.

That said, if when you are editing you render a clip by hitting the Enter key on your keyboard... for example to get the video to play back smoothly or to see an applied effect, PE7 will generate a temporary "render file" that replaces the video on your timeline and this file will remain on your computer until you delete it. This "render file" is an MPEG2 file. So... if you edit MPEG2 you may not need to render portions of your timeline and so you will not generate these MPEG2 render files. Whereas if you edit AVCHD/MP4 you will probably need to render your timeline thus generating large MPEG2 files.

If you are really restricted on harddrive space to the extend that you are concerned about the extra size that an animated title might add then I think you are going to be in for trouble , as when you export your timeline it will be rendered.. and this rendered file will be MPEG2. May be time to buy an external USB hard drive!

You information is valuable, I'm sorry I'm struggling to understand. I don't appear to be running out of hard drive space when I work with editing AVCHD... 40GB are free currently without doing anything. Or, is 40GB of free disk space not enough to work with a 7-minute AVCHD file?

Are you also saying there are hidden MPEG2 "render files" somewhere on my machine that I should delete after I've exported to mp4? (because yes, I do hit enter to render, as the playback without that is very choppy).

60% savings in final size over MPEG2 seems quite worthwhile, thank you for that figure. No, I'm not concerned about one animation effect, unless one clips adds 10 MB to the final mp4 size, and I'm wishing I could have 20 such clips. My ultimate goal is try to produce a 10-minute HD video that stays under 600 MB, the current requirements for SmugMug. (I believe Bob? on another thread tried to tell me about bitrate exporting but I confess I didn't understand that part... will have to go back and study.)

I do have an external USB drive, but is the question how many GB of working space does editing a 7 minute AVCHD file need, and whether I need to go find old MPEG2 generated garbage files, and delete them? PE7 does repeatedly freeze while I'm working, including sometimes simply disappearing from the screen without warning freezes. I watch the task manager RAM climb to above 2 GB and I try to shut down and re-open (not restart the computer though, hope that's not necessary) before it crashes, but I can get preoccupied and wait until it's too late. I also get "PE is running out of memory" which I have guessed is virtual memory. If I'm doing the best I can by editing AVCHD, then I suppose I will have to conclude that the crashes are a consequence of my inadequate machine.

[Paul LS]

40GB is more than enough for a 7min AVCHD file... but would be pushing it if you were editing an hour video.

You can delete the MPEG2 render files that PE7 creates by going to the top of the screen and selecting "Delete render files" which is under one of the headings... not at my video computer so cant recall which one at the moment.

Regarding effects and titles, these add no additional size to the exported movie. When you render for export the effects/titles are "burnt" into the movie and the only thing that determines the final file size is the codec used and the bit rate. You will be able to get 10 minutes of HD video under 600MB using MP4 but you will need to reduce the bit rate on export. Probably best to do a few trials... reducing the bit rate each time. Also how about exporting to 1280x720, this would generate a smaller file size.

[ChancyRat]

40GB is more than enough for a 7min AVCHD file... but would be pushing it if you were editing an hour video.

You can delete the MPEG2 render files that PE7 creates by going to the top of the screen and selecting "Delete render files" which is under one of the headings... not at my video computer so cant recall which one at the moment.

Regarding effects and titles, these add no additional size to the exported movie. When you render for export the effects/titles are "burnt" into the movie and the only thing that determines the final file size is the codec used and the bit rate. You will be able to get 10 minutes of HD video under 600MB using MP4 but you will need to reduce the bit rate on export. Probably best to do a few trials... reducing the bit rate each time. Also how about exporting to 1280x720, this would generate a smaller file size.

Doesn't 1280 x 1080 allow the viewer the largest size to view?
How do I know if I'm using the right codec? (Haven't a clue about that.)
If I do trials on bit rate, what am I looking for/at when I compare? (Haven't a clue about that.)
Finally, how do I change the bit rate? I have (I think) verified the variable bit rate is in the preset. Then, when I'm ready to export, select 264, 1920 x 1080 30i, then advanced settings, and - then I'm lost. I don't see how to change it, using alaskamovieguy's instruction when he said:

... I don't think you are going to get any smaller file for HD than the H264 but you can create a smaller file by controlling the bitrate when you export from PE7. On the preset click advance and in there you can choose 'Constant Bit Rate' or 'Variable bit rate'. The variable bit rate will give you the smallest file, you may have to play with the settings there to get the desired file size. The smaller the bitrate the smaller the file size. I might try about 3000 for the minimum and 8000 for the maximum, also the quality slider will affect the file size. ...

There needs to be a 'light at the end of the tunnel' emoticon.