Poor sound quality

kirkdickinson wrote on 12/14/2009, 9:30 AM
I am trying to put together a music video for a Christmas program. We did the video two years ago with Sony Vegas 7. I am now on 8.0c

The music track had to be changed and the source files were midi and came from Garageband on my mac. I exported as MP3 and changed the audio on the time line and rendered out as MPG.

The sound is crap. It wavers and sounds like a worn out tape dragging a little.

I have rendered the video and audio separately and built a DVD with Architect and the sound is the same there.

I have gone back and listened to the MP3 and there is a noticeable difference in what is coming out of Vegas than what is going in.

I have tried rendering the MP3 file at 320 from Garageband before bringing into Vegas, but that doesn't make a difference.

The original that I had also came from Garageband, and it sounded fine.

What should I try next to get adequate sound?

Maybe I will just render the video only and put the sound and video together on the mac side since Vegas is failing to render the audio at acceptable quality.

Any other ideas?

Thanks,

Kirk

Comments

rs170a wrote on 12/14/2009, 9:34 AM
If Garageband can export a WAV or AIFF file, that would be preferable (and higher quality) to MP3.

Mike
kirkdickinson wrote on 12/14/2009, 11:34 AM
Well, I am wondering why the same type of project worked 2 years ago with good sound quality and now it isn't?

Just exported the video and took it to iMovie (which sucks) put the garage band mp3 into it and exported and the sound is acceptable.

I just wonder if there is some export setting that I should use, or should I convert the MP3 to wav before re-encoding to MPG from vegas?

Thanks,

Kirk
musicvid10 wrote on 12/14/2009, 11:40 AM
Vegas doesn't degrade the audio from any source -- so maybe it is what you are asking Vegas to do with your mp3 files.

--What are the bitrate, sample rate, and bit depth of your source files?
--What are your Audio Project Properties? Is Resample set to Best?
--What are your Audio Render Properties? Are you asking Vegas to upsample your audio?

Since you report bad playback of the rendered files, not just on the timeline, I suspect looking at the 3 factors above will point you to a solution.
kirkdickinson wrote on 12/14/2009, 6:35 PM
Am not by my PC right now. Only have the Macbook. I noticed after my last post that it plays badly from the timeline also. Rendered sounds are about the same as from the timeline. MP3 played in iTunes or Windows Media sounds fine.

I can't imagine what the deal is. I have never had any audio problems with Vegas before.

I will post all the bitrate stuff tomarrow.

Thanks,

Kirk
kirkdickinson wrote on 12/17/2009, 11:06 AM
Source:
bitrate 320 K
Frequency 44100 (can't find rate and depth)

Audio Project Properties:
Stereo
Sample 44,100
Bit Depth 24
Resample Best

Here is the MP3 from Garage Band:
http://www.ajoyfulministry.com/temp/mary4.mp3

Here is a clip from the video out of Vegas:
http://www.ajoyfulministry.com/temp/mary4.mpg

The audio in Vegas has no adjustment, volume set to 0.0 db -/+ no track effects.

It is rendered to mpg using MainConcept MPEG-1 Default Template
Audion 224Kbps, 44100 Hz, Layer 2
Video 29.970 fps, 720x480

Thanks,
Kirk
musicvid10 wrote on 12/17/2009, 11:25 AM
Here is the MP3 from Garage Band:

Gives an error that the file does not exist.

http://www.ajoyfulministry.com/temp/Mary4.mp3
This works.
Remember that URL file locations are always case-sensitive.
kirkdickinson wrote on 12/17/2009, 11:45 AM
Sorry, I just realized that was a linux server. Case sensitivity. <bites me every time>

Just renamed the file to match the link.

Thanks,

Kirk
dlion wrote on 12/17/2009, 11:47 AM
render the video only using the mainconcept mpeg-2 template (uncheck audio stream in audio tab).

then render the audio using the dolby digital ac3 studio template.

then bring them into dvda.
kirkdickinson wrote on 12/17/2009, 11:48 AM
I think I figured out what the problem is with this file.

I placed the entire clip on a parallel audio track and noticed that the newly placed file is shorter by 8 seconds.

I see that the clip was stretched 8 seconds for some reason. Maybe to better fit the original video. I thought that stretching would render better than it has. New file is ok without crappy sounding output.

I think the problem is solved. I hope so.

Thanks for helping me troubleshoot this.

Merry Christmas,

Kirk
farss wrote on 12/17/2009, 11:50 AM
Unless the video is over 60 minutes there's no need to use ac3.
Seeing as how the original mp3 is 44.1KHz and the target is 48KHz I'd suggest changing Vegas's Resample Quality to Best.

Bob.
kirkdickinson wrote on 12/17/2009, 11:51 AM
Dilion, I had done that for the DVD that we use to play the video some places, but I also needed an MPG to play on different computers that may or may not have DVD.

See last post, I think I have the problem solved.

Thanks,

Kirk
musicvid10 wrote on 12/17/2009, 11:58 AM
You would use a media information utility, such as MediaInfo to find your media properties.

Your audio is 16 bit, and that is how it should be set in Project Properties, although that is unlikely to affect the output in this case.

Any MIDI generated audio source, like GarageBand, contains quantization noise. Any resampling of that audio exaggerates quantization noise, sometimes dramatically. In this case, downsampling from 320 to 224 has caused some of the differences you hear. You would likely hear an improvement if you rendered at 16/44, 320Kbs. Also, MPEG layer 2 audio is a less than ideal output container for music. Likewise, MPEG 1 video is a less than ideal output container for video.

If your use is for the web, the Sony AVC/AAC container is preferable for many reasons, audio quality being one of them. Match the media sample rate, bit depth, and bitrate exactly, or process the audio first in Sound Forge with appropriate dither and anti-alias. This precaution is usually not necessary with non-midi generated audio.

EDIT: If your audio was stretched the way you say it was, that would introduce quantization and flanging. Lots of it. I'll stick with my advice though, since it is good practice when dealing with midi generated source.