dv to xvid: a couple questions

[greymalkin]

before i perform the long process i just thought i'd ask a few general questions.

I have recorded some footage on my dv camera using a tripod so shaking..etc is at a minimum. My firewire port does not work on the camera, however, so i capped it as an uncompressed .avi, did my edits, then rendered to mpeg2 @ 9336kbps (procoder doesn't allow anything above that?)...anyways..i would like to now make a more portable version by resizing to 352 x 480 and compressing to an xvid file.

The video is 26 minutes long.

Here are my questions:

1) When watching the xvid file, will media player/the xvid codec stretch it out to make it look normal like it does with 352x480 mpeg files?

2) I used an xvid bitrate calculator, but it was not very thorough as it didn't even let you put in the resolution of the file in the same page where you chose bitrate..etc. It claimed that at a video bitrate of 1450 and an audio bitrate of 96 my results would be "very good" and take up 300mb.

I'm familiar with bitrates when talking about mpeg2 but when we get to the more compressed formats I don't know what to expect.

thanks

[celtic_druid]

1) XviD will stretch however there is a bug so it won't work if you encode with bframes that aren't packed. Also won't work if unless you actually set the AR so that the decoder knows to resize. ffdshow, VLC, DivX, mplayer, etc. also support PAR resizing.

2) Resolution has nothing to do with bitrate.

[greymalkin]

are you saying that if I took a 720 x 480 video and compressed it to MPEG using a bitrate of 3.5mbps it would look just the same as a 352 x 480 MPEG at 3.5mbps?

I'm not understanding the comment "Resolution has nothing to do with bitrate" if my question was read and understood properly as everything i've heard up until now is just the opposite.

I was in no way suggesting that resolution and bitrate are the same thing, but in order to determine what the file size would be and what a good bitrate would be for the video the resolution of the file is a factor..therefore having MUCH to do with what the bitrate should be.

[celtic_druid]

are you saying that if I took a 720 x 480 video and compressed it to MPEG using a bitrate of 3.5mbps it would look just the same as a 352 x 480 MPEG at 3.5mbps?

Not at all. All I was saying is that it would be the exact same size. Potentially it (352x480) could actually look better though.

[junkmalle]

If you don't care about the exact file size use Xvid's Quantization mode. Pick the quality you want and encode in a single pass. Each frame will have the quality you specify. Try Q values between 2 and 4 (the lower the Q value, the higher the quality).

[greymalkin]

i think i may have to go the bitrate route as I'll be putting it on my website which only allows for 500mb of space..if i can shrink it to 352 x 480 and use a bitrate of 1450 to get good quality that is what i'd like to do.

thanks

[junkmalle]

Note that you have to be using a fairly recent version of Xvid for 352x480 files to play at the correct 4:3 aspect ratio. If you are making the video available to a lot of people you should stick with a 1:1 pixel aspect ratio (640x480) because you can't be sure your downloaders will have a recent Xvid release.

You will also have problems with interlace -- there aren't many players that will deinterlace interlaced Xvid AVI files for playback on the computer. Everyone will see interlace comb artifacts.

[greymalkin]

i actually deinterlaced it when I encoded it from the mpeg that will go on the dvd to the xvid file. I went ahead and resized it to 352 x 240 as well. I ended up with a 200mb file which was acceptable. I probably should have set the quality settings alot higher as I was willing to make it up to 300mb but oh well what is done is done..it looks great at 1x zoom and it's watchable at 2x...it's kind of an informal "sneak peak" at a wedding video i'm doing for a friend of mine. The bride's sister went off to italy for a month right after the wedding and she wanted me to give her a "rought draft" of the wedding video to take with her and show the person she is staying with there..well I was having some capture issues that junkmalle figured out for me (thanks again!) so I didn't even get what I considered an acceptable rough draft ready in time.

Anyways..once i went back and captured it properly, edited the video for the wedding ceremony itself, and did some quick and dirty audio cleanup i went ahead and slapped it together and compressed to xvid. I sent the bride's sister an e-mail with the link to the video as well as the xvid codec I used so they can play it back. The audio is standard mp3 96kb/s.

So for now the video portion of the wedding ceremony is done, but i still need to work on the audio some more. I'm excited about this project as I am going to try and make a DD5.1 disc. I recorded the wedding with 2 cameras, one up close (on the 2nd row) to get good audio and one in the back. I am going to try a reverb reversal technique that BJ_M posted a few weeks ago to try and get a "dead" vocal track to put right in the center channel. Then in the FL and FR speakers i'm going to split up the original "close up" voice only track for some of the light ambience. Lastly I will put what my camera got of the voice in the SL and SR speakers to fill in the room. I know it will take alot of time tweaking with the volume levels to get it to sound good but i'm hoping it turns out...that way I will have created somewhat the ambience of the room while bringing out the voice. For the music before and after the wedding I will have it playing out of the fronts and surrounds..just not the center. The music and the voice part of the wedding do not occur at the same time.so it makes it easier..

and if i can't get it sounding good i'll just go back to the good ol' stereo mix :P

[whitejremiah]

2) I used an xvid bitrate calculator, but it was not very thorough as it didn't even let you put in the resolution of the file in the same page where you chose bitrate..etc. It claimed that at a video bitrate of 1450 and an audio bitrate of 96 my results would be "very good" and take up 300mb.

I'm familiar with bitrates when talking about mpeg2 but when we get to the more compressed formats I don't know what to expect.

thanks

in reguards to the bitrates, and such.......i'd personally go quite a bit higher on the audio part, myself...i'd let it go to like 224k/s so there's not much distortion in the audio, though, on the video bitrate...depending on how much movement there is, 1400k may be good enough to work.........seeing that it's recorded from a DV camera (unless you were recording something like a chemical explosion or something like that) 1400k/s would probably sufice.......best bet though, is to try 1400k/s see if it looks acceptable to you, if not, i'd jump it up to like 1600 or 1800.......just toy around with the file for a while and see what looks right to you.

[greymalkin]

i'll definitely do 224kb/s AC3 on the DVD, but this project was concentrating on a small file as well..since most of the wedding ceremony is just speaking, i didn't see a need for using the extra bandwidth...

this is just a "sample" if you will of the actual video for one person who is halfway across the world..the internet was the quickest and easiest way to get it to them. The DVD is where i will spare no expense (in a figurative sense).

While i'm on my rant about this dvd i'm oh so excited about..what is the difference between using procoders mastering mode @ 9336kb/s video bitrate as opposed to it's max (1) CQ setting? which should yield better results? the file size in this case is not a concern as the wedding and reception together will be under an hour after all edits...etc.