Advanced video editing questions

[drick]

hi,

i'm trying to figure out how to best edit some video shot using my helmet cam, and am having all kinds of issues. here is my set-up:

1. 20/20 helmet cam that captures video at 656x492 (with 480 Scan Lines) @ 30 FPS

2. Aiptek MPVR digital camcorder that captures video at 640 x 480 @ "up to 30 FPS". The units default capture medium is MPEG4-ASF.

3. Editing will be done on WXP Pro SP2 using either Adobe Premier Elements 3 or Roxio EZ Media Creator 9

Neither PE3 or EMC9 will accept the ASF files natively for editing, so i'm using an encoder to change them into AVI files which both accept. The encoder is made by Arcsoft, and it's v 2.5. Here are the settings i'm using for the encoding:

file format - mpeg4 avi
video encoding - arcsoft mpeg4 codec
video bitrate - 3 mbps*
fps - 29.97*
resolution - 640x480
audio encoding - arcsoft mpeg1 / layer2
audio bitrate - 192kbps*
audio sample rate - 48 khz*

*maximum setting allowed

My challenge is that i THINK i'm losing some quality during the conversion process, and that the video will look better if i could import it at a higher quality?

So my questions are:

1. Am i really losing any quality by converting with the above settings? It's been suggested that 8 mbps is the magic number for encoding.

2. If answer to Q1 is yes, does anyone know if VS11 will support encoding MPEG4-ASF in and AVI & DV-AVI out at 8+ mbps?

Thnx
D

[DVDDoug]

What are you doing with the final video? Are you making a DVD? A computer "AVI" file? A file to upload to the Net?

1. Am i really losing any quality by converting with the above settings?

In theory, yes. But, depending on what you are converting to, it might not be noticeable... All of the video compression schemes use lossy compression, and data is thrown-away every time you encode.

It's been suggested that 8 mbps is the magic number for encoding.

It depends on the type of compression. For MPEG-2, that's very good "DVD-quality". DVDs are MPEG-2 and 5-6 Mbps is "typical" for commercial DVDs. 8Mbps MPEG-4 is overkill for your files (It would be on the low side for high-definition video).


------------------------------------------------------------------------
Higher bitrate = higher quality = bigger file size = lower compression = less playing time.

Lower bitrate = lower quality = smaller file size = higher compression = more playing time.
------------------------------------------------------------------------


Ideally, you would compress once to the final format. If you need to re-code, it's best to re-compress once, to the final format. And, use a "high" bitrate for the final file. How high? ...It depends...

For example, if you convert a 3Mbps MPEG-4 file to 3Mbps MPEG-1, you will see the deterioration. If you convert a 3Mbps MPEG-4 file to 7Mbps MPEG-2 (good DVD quality) you probably will not notice the deterioration from the 2nd encode.

2. If answer to Q1 is yes, does anyone know if VS11 will support encoding MPEG4-ASF in...

I don't know the answer. Have you downloaded the trial version? Lots of ULEAD users do have trouble with MPEG-4. There are many variations of each format, so you'll have to try your particular files. The more compressed the format, the more likely you are to have problems. MPEG-2 sometimes causes trouble, DV almost never causes trouble.

...and AVI & DV-AVI out at 8+ mbps?

Yes. Video Studio can make AVI/DV. But, DV is not 8Mbps... I forget the number, but it has a fixed bitrate (~20Mbps?). DV is less-compressed than MPEG (bigger files and higher bitrate).

Depending on what you are doing, it might be best to convert the file to DV, do all of you editing in DV, and then convert to your final format. This does involve an additonal (lossy) encode step, but because DV is less-lossy than MPEG-4 you shouldn't notice it.


You will also get some deterioration if you change the resolution. Pixels will have to be added or removed. The same is true if you change the framerate (FPS).

If you are making a DVD, the resolution and framerate will have to be changed for DVD compliance.

If you combine files with different resolutions/framrates/bitrates together, the output file will have the same settings throughout. So, at least one of the files will have to be changed to match the other(s).

Editing will be done on WXP Pro SP2 using either Adobe Premier Elements 3 or Roxio EZ Media Creator 9... using an encoder to change them into AVI files which both accept. The encoder is made by Arcsoft...

If you are not getting good results, you might want to try SUPER to re-code the file. It's a FREE universal A/V conversion tool, and it's probably got more output-format options than the Arcsoft program.

[drick]

Doug,

I will be making a final DVD from this footage.

after much ado i found a incrementally better conversion method talking to arcsoft. without changing the resolution from 640 x 480, i can convert from mpeg4-asf to mpeg2 with these settings:

mpeg2
640x480
6mbps*
29.97fps*
audio bitrate 384*

*maximum setting allowed

i assume that this will be better than the old method, and that i can edit (understanding that it's not optimal) this format?

[Ken Berry]

The major problem remains that 640 x 480 is NOT part of the DVD standard, so to burn it to a DVD, it will still have to be converted to one of the DVD standard frame sizes such as 720 x 480 or 704 x 480...

[drick]

The major problem remains that 640 x 480 is NOT part of the DVD standard, so to burn it to a DVD, it will still have to be converted to one of the DVD standard frame sizes such as 720 x 480 or 704 x 480...

ken, i can convert the source all the way up to the specs below, but i don't think that is what you are suggesting is it?

The highest quality conversion of MediaConverter 2.5 is MPEG 2 format:
Format: MPEG-2
Resolution: 1920X1440
Video Bitrate: 24Mbps
FPS: 29.97
Audio Bitrate: 384Kbps


p.s. the helmet cam is recording at very close to that, and i can't change that part

"The 20/20 helmet cam captures video at 656x492, 480 Scan Lines, and 30 FPS. "

[Ken Berry]

No that is not what I mean. For a standard video DVD, the frame format size has to conform to a limited range which is set in the formal, internationally recognised standard for what makes a DVD. In the full frame size for NTSC it is either 720 x 480 or 704 x 480. There are also half frame sizes too. But unless you can set your cameras to film in a DVD-standard frame size, then any video filmed with them will have to be converted at some stage.

[drick]

No that is not what I mean. For a standard video DVD, the frame format size has to conform to a limited range which is set in the formal, internationally recognised standard for what makes a DVD. In the full frame size for NTSC it is either 720 x 480 or 704 x 480. There are also half frame sizes too. But unless you can set your cameras to film in a DVD-standard frame size, then any video filmed with them will have to be converted at some stage.

so maybe i should convert it at 720x480 the 1st time? it will accept 8mbps that way.

what do you think?

[Ken Berry]

That is probably what I would do. And using a bitrate of 8000 kbps would at leave minimise any evident loss of quality caused by the conversion.

[drick]

That is probably what I would do. And using a bitrate of 8000 kbps would at leave minimise any evident loss of quality caused by the conversion.

thanks for the suggestion, i already converted it, now i get to go edit it again..

[harry_hariz]

hai bros...help me figure out what is really pofessional video editing software..i wonder if avid is one of world class edting system..could u all names up the software?