Low Level Fizzing Audio Artifacts in DVD Encoding

[djspearritt]

Dear Forum

I am noticing some very low level fizzing noises in the DVD exported VOB files when exporting from Edius 4 Pro and ProCoder Express.

Here is a sample with the gain turned up.
EdiusProCoderEx_SoundArtifact

The source files in the project sequence are pristine 48k 16 bit files so should not need any "encoding" further, but they seem to be contaminated with this low level noise. Playing direct from the sequence in Edius is pristine.

Any ideas why this is so and how does one fix it. I tried to install the update for ProCoder Express but it wants a serial nr and I don't have one, only an Edius 4 Pro Serial nr.

Regards
David Spearritt

http://www.lodestarrecordings.com.au

[djspearritt]

Update

Found the problem, the audio output format in the last "advanced options" screen was set to MPEG and not PCM. Reprinted with PCM and all is fine.

Two issues remain.

1. The MPEG encoding of audio contains fuzzing artifacts, not very good!
2. How does one update ProCoderExpress that comes with Edius 4 Pro, where is the serial number?

Regards
David Spearritt

http://www.lodestarrecordings.com.au

[SRsupport]

One would install an update for Edius and one would see that pce for Edius gets updated . One would not need a serial number. :)
So it might be that one downloaded an update that was not intended for pce that comes with Edius. he he
SR

[djspearritt]

Well one might be tempted to say that one should place this information clearly on one's website, where one's updates are listed. :)

Any comments on the fizzy artifacts in the MPEG audio encoder?

Regards
David Spearritt

http://www.lodestarrecordings.com.au

[SRsupport]

Give the original file and I can encode to listen to the results and compare it to yours. The file that you put up has an extra encoding step.

[djspearritt]

Here is the original 48/16 WAV.

http://www.lodestarrecordings.com.au/ftp/uploads/original.wav

[djspearritt]

Bump bump.

[SRsupport]

That wav level is way to low to hear I the artifacts are present in it. You have to apply a great amount of gain before you can imagine to hear something.
Can't do a test with this sorry.

SR

[djspearritt]

But I posted the gained up encoding artifacts in the first file in this thread. The artifacts are clearly audible. For a classical music video application, these artifacts are a serious problem with this encoder.

I hope Canopus will take this issue seriously.

[tingsern]

Hi,

I downloaded your original WAV, and passed it thru ProCoder 3. Output as 192KHz MP3 file. I then did a spectrum analysis on both WAV and MP3 using 16384 samples FFT and Blackman-Harris algorithm. The outputs can be been as attachments. I would say that there is NO audible difference between the original and the MP3 file.

In both cases, you are listening to "sounds" at -80dB on average. Looking at the FFT, the MP3 is quieter than the original.

TS

[djspearritt]

Many thanks for your efforts, but I am using ProCoderExpress inside Edius 4 Pro. It seems the problem is with ProCoderExpress, not ProCoder3. These artifacts are clearly audible when playing the DVD, just before the music starts.

If I take the same WAV file and convert it to MP3 in Wavelab, there are no artifacts generated.

[tingsern]

Can you post me the following items - (a) the non-amplified MP3 sound (output directly from ProCoder Express), (b) the parameters you passed to ProCoder Express to generate that MP3 from the original WAV file? I will do some experiments and see if I can tell where that "extras" come from?

Generally, to "compress" sounds - the MP3 or AAC algorithm looks for "symbols" to substitute - if it can't find any (like in your case), it might magnify random noises (aircons, microphone noises, etc).

Fact is your original all contain sounds at -80dB from 1hz all the way to 500hz. Did you turn on the mic's low frequency filter to cut off 30hz and below? I haven't seen a microphone good enough to capture 30hz without distortion. 50hz - fine.

*** More info ***
I went into ProCoder Express for EDIUS to try to convert your original WAV file to MP3. Under "Load Source", I can't even find WAV as an acceptable input medium for this program !!! I wonder how you managed to convert your WAV to MP3 then? For that matter, I think ProCoder Express is only accepting VIDEO files as valid input, not pure AUDIO files.

[tingsern]

Okay - what I did was to use EDIUS to open the "original.wav" file, drag the audio file into timeline, and then export the timeline to file, using ProCoder Express. I specified "DVD", and "MPEG1 Layer 2" - so, it gave me one video file (which I deleted), and one audio (m2a). Did a spectrum analysis of the m2a file (same parameters as original and MP3 *encoded by ProCoder 3*) - the output of which you can see below. It is just a bit noisier (by 2 or 3dB) - but, you have to bear in mind this noise is at -70dB ... which is basically below the floor noise of most audio amplifiers.

In short, I still can't reproduce your noise problem.

[djspearritt]

I am not interested in spectral analysis, or in how many dB the level is down. The fact is that there are artifacts which are clearly audible (ie. with one's ears, not a spectrum analyser!) and objectionable and they are associated with the MPEG2 audio decoding of ProCoderExpress.

I hope you pursue this and sort it out. Artifacts, by their very nature will always be at a low level, but this certainly doesn't mean that they should be ignored. It points to significant errors and corruption in the encoder. One cannot take this encoder seriously until these artifacts are removed.

Regards
David Spearritt

http://www.lodestarrecordings.com.au

[tingsern]

Hi David,

May I point out to you that I am just a user (like you). You probably thought I was a Canopus developer / tech support - for which I am certainly not. I was trying to help you figure out the source of the problem.

Please refer to the previous note (which I requested the original noise WAV - without amplification) and the settings you provide ProCoder Express with. I can try to recreate the problem and see if I can tell what is wrong?

On a side note, have you applied ALL the fixes to EDIUS and Procoder Express that are applicable (download them from Canopus website)?

Cheers,
TS