Audacity Forum

Hello all,

We recorded a carpentry workshop using the GoPro Hero2 camera and are putting it on a DVD to share with others. It has been an adventure to try to figure out all the variables but anyway we now have a video assembled but the sound quality is not good when burned to a DVD (sounds OK on the computer). I have read that audio in 256 Kbps is much better. My concern is that since the GoPro MP4 video clips were only recorded at 128Kbps/48 Khz it will do little good to set up Windows Movie Maker to dedicate 256Kbps to sound instead of 128. Am I wrong? I have run the audio thru Chris's Audacity audio compressor and that seems to help bring up low volume parts (we had to film with the camera in it's H2O case because of wind noise) but it is still not very clear with lots of back ground noise. Any ideas would be appreciated. wh

whp wrote:... I have read that audio in 256 Kbps is much better. My concern is that since the GoPro MP4 video clips were only recorded at 128Kbps/48 Khz it will do little good to set up Windows Movie Maker to dedicate 256Kbps to sound instead of 128. Am I wrong?

Re-encoding audio in another lossy compression format can only make audio worse : it cannot improve it.
Using 256kbps will cause less additional compression damage than using 128kbps

It sounds like your main problem is high levels of background noise ,
if you post a little bit of the audio we will be able to tell you if improvement is possible.
( don't get your hopes up : if the camera was in a water-tight case the sound will inevitably be muffled ).

Thanks for your note. I attached a WAV sample as suggested. I suppose I could try the Audacity noise reduction effect but the voice is not very clear.

I also didn't understand what you were saying about 256 vs 128. It sounded like you were saying to use 256 even though GoPro only records at 128Kbps and 48 kHz. Did I misunderstand ? wh

whp wrote:Attachments
DVD 1 WAV sample.wav
sample of video voice
(797.12 KiB)

IMO applying equalization which cuts the bass makes it sound a bit less muffled ...
You can copy the above EQ "curve" manually into Audacity's equalizer
or add it as a preset curve by importing it into Audacity's equalizer via the XML file attached below ...
http://manual.audacityteam.org/man/Equalization After applying the equalization you'll probably have to apply amplify at the default 0dB setting to avoid clipping.

Compressing sound creates some quality damage. They all do it, AAC, M4A, MP3. The problem comes when you do some production and then make a new compressed file. The new file will contain the compression damage of the first file plus all the new junk. Two 128 in succession has about the quality of one 64. The only way around it is the second compression has to be really high so as not to contribute to the problem. Ideally, you'd be up in the 256 or higher range. What's the next one 384?

I have a periodic production that I save in uncompressed WAV so as not to make it worse. Stereo WAV is around 1400 quality.

Koz

OK Trebor and Koz. Thank you both. First, I will try the equalization process and see if it helps and then select 256Kbps when setting up sound in an application used to size the material to fit a DVD in MP4 format. Struggling with that now. I zoomed many of the GoPro clips with their program and assembled the DVD in Windows movie maker (Windows 7). wh

With the benefit of hindsight my EQ curve above removes a bit too much bass.
Here's a preset for a similar curve which doesn't remove as much bass ...