Project exports mp3 with warbling distortion?

[Gale Andrews]

I was going to ask if there would be ANY benefit to converting the MP3s to WAVs (using Audacity) prior to merging them with the JPEGs. If so, then I could go with Steve's second 'The Better Way is:' suggestion.

The benefit of WAV is maintaining the quality of the audio before any (or multiple) lossy compression steps that may be required. It may be quite difficult to find free (or any) DVD creation software that also includes video editing features so it can take a batch of images and string them together with audio files into a video file. If the DVD writes AC3 (lossy) audio as expected and you have to use a video editor first to produce a video file, then you can avoid lossy compression before the final DVD creation step if you provide lossless audio in the video file.

Depending on the DVD authoring software it may provide LPCM audio output, which is uncompressed and lossless (there is a circa 2:1 compressed variant which is also lossless).



Gale

[cptroc]

From what I have found after hours of reading many forums, trial and error is clearly the norm for these type of projects (knew this going in). Success varies when using .WAV, .WMA, or .MP3 audio formats. It might serve my project if I take the group of MP3s I want to use, convert them to the three audio formats (.MP3s need balanced bit rates, use MP3Gain to balance .MP3 audio levels). Should I balance the bit rates and audio levels of the .MP3s prior to converting them to .WAV and .WMA? That will give me three sets of audio files to work with in preparing the slideshow. It might serve me well if I create a DVD Jukebox (Roxio) of each audio set, and play it on a few DVD players (non-computer), to get an ear on how the audio sounds BEFORE letting Photo Story 3 do its thing.

What do you think?

[steve]

The aim is to keep the sound quality loss as small as possible at each stage.

As your "original" audio is MP3, you can't do anything about the compression at that stage.
In Photo Story 3, set the audio quality as high as possible. If Photo Story 3 supports a lossless format, use that, otherwise use the highest quality setting available.
When you burn to DVD it is likely to be burned in a standard format, so the "quality" setting there is probably fixed.

The place that you can probably make a difference is in the Photo Story 3 settings. Adding additional conversion steps is unlikely to produce any improvement and may make the sound worse.

[cptroc]

Thanks for all the assistance do far.

Sothink Movie DVD Maker does allow the user to change a few of the audio settings; (1) bit rate (up to 448bps), and channel (mono, stereo, 5.1)

Photo Story does no appear to provide any audio changing settings for imported audio. It cannot use .WAV files with more than 2 channels, higher than 16-bit sample size, or more than 44,100 Hz sample rate, accoring to its website. It also appears that Photo Story 'prefers' .WAV and/or .WMA formats.

Looks like I have a trial and error day ahead of me.

[Gale Andrews]

Should I balance the bit rates and audio levels of the .MP3s prior to converting them to .WAV and .WMA?

It would seem sensible to set the amplitude of the MP3s to about the same level in Audacity - there is no encoding loss if you export as WAV, and 16-bit stereo 44100 Hz is Audacity's default WAV export, so the video editor should accept it. 16-bit stereo 44100 Hz WAV export will set the bit rate of all the files to 1411 kbps, though this does not of course "improve" the sound quality just prevent it getting worse than it already is.

You can use Effect > Normalize to your chosen level on all the tracks at once, if you are OK with any volume level discrepancies between left and right channels of the same file being ironed out. Otherwise, use Effect > Amplify on one stereo track at a time.



Gale