wmv is jerky and loses sync
by Fred Casanova
on
Aug 16, 2008 at 12:30:05 am
I'm a newbie to encoding video for web and looking for answers to my troubles. I have a prospective client that wants his video encoded to wmv. I'm using Episode 4.4.1. I have extracted a test segment from his camera video on DVD and have been sending a wmv to him so he can put on his site to see how it performs. He is testing on a very fast connection and then on something slower. He says the fast connection many times loses sync and is generally worse than the slower connection. This is somewhat counter-intuitive to me, but I'm a newbie. He also says video is sometimes jerky. In one of my tests just running the wmv on my machine, the wmv was jerky too but played better when I put in on my website. What gives? Do I need to know what his host is running? Streaming vs. progressive download? I have tried the wmv9_768kbit preset with 2-pass VBR and 2-pass CBR. I have varied the frame size, but anything below 480x360 seems soft. I put audio down to 32 kbps 44.1kHz mono, but he says is sounds tinny, so I'll probably bump that up. Is multi-bit-rate the way to go or should a medium or high bit-rate be sufficient? Thanks for reading all this.
Fred C.
Re: wmv is jerky and loses sync by Craig Seeman on Aug 16, 2008 at 3:48:55 am
Update to Episode 5.0.1.
It's hard to know what your client's internet connection is, what the capabilities of their computer, what player they are using. You also don't say what you're using to view the file.
Can you post a link so I and others here can check? If the material is confidential use an equivalent source with the same preset you mentioned above. At least some of us can ballpark what the issue might be.
Re: wmv is jerky and loses sync by Fred Casanova on Aug 16, 2008 at 11:29:36 pm
I viewed this on a Mac that I just tested the connection speed. Upload is 357, down is 550. The test video is slightly jerky in spots when he moves from side to side. This might be due to 15fps. I added a 10sec clip of pulsing tone and pulsing color bars to check that he was seeing that in sync. Yes, that looked in sync to him and me, but his video looked a little jerky to me. He said it was very bad on a very fast connection.
This is the test on his site-- http://www.highnoi.com/BobPetersonTest8.wmv Fred
Re: wmv is jerky and loses sync by Craig Seeman on Aug 17, 2008 at 12:24:39 am
[Fred Casanova]"Upload is 357, down is 550" kbps? I guess everything is relative but that's a moderately slow DSL speed. With 550kbps down I'd keep that data rate to 300kbps to provide headroom for possible speed variations.
[Fred Casanova]"This might be due to 15fps." I'd generally use the source frame rate (29.97fps, NTSC 25fps PAL, 23.98fps NTSC "film" rate) but if his down is 550kbps I can understand going to 15fps to maintain sharpness at the cost of temporal resolution (motion smoothness).
By comparison I get 30,000kbps down and 5000kbps up give or take although I do have one the faster providers in the country. Generally though I'd consider 5000kbps down a decent fast CableModem speed 1500kbps or 3000kbps a reasonably fast DSL speed. Many parts of the country still have 768kbps which is what it sounds like your client has.
Using the 768kbits preset might be just a bit high for his connection. You should try 512kbit or 384kbit preset
Re: wmv is jerky and loses sync by Fred Casanova on Aug 17, 2008 at 2:17:13 am
Craig, thanks for your input. FYI, the connection speed I mentioned was from my home computer, not my client's. I'm not sure what his speed is. He uses 2 different locations at 2 different speeds, one "very fast", whatever that means. I will try a slower bit rate to see what kind of difference that makes. But I'm still confused how to handle the wide variety of connection speeds that may access his site to play his videos. Do you have a favorite bit rate to encode with that works for most? Is a multi-bit-rate encode the answer for wmv? I'm not sure if a multi-bit-rate encode depends on the hosting server or should I be able to upload it to any host without issue?
