MPEG-4 Audio Recording Sounds "Boxed In"

[greenbook]

An acquaintance of mine just send me 5 minute audio clip of her speaking. It's a MPEG-4 (.m4a) clip recorded at 194kbps. The sound is okay, but it sounds boxed in. I believe the audio was recorded in a small bedroom - I'm not sure, I can ask her.

The real problem with the boxed in sound is if I take the clip to any audio editing software like Audacity or Roxio, and I attempt to do a pitch shift to make her voice be a little higher, the sound becomes extremely warbly and even more boxed in.

Anyone have a solution to this problem? Does she need to record the clip in a larger room? Does she need record at a better sample rate than 194kbps? Is there any audio editing thing I can do to reduce the "boxed in" sound?

Thanks for your assistance.

[greenbook]

The audio was recorded using a Panasonic LUMIX DMC-FZ70 Digital Camera in a fairly large room.

[KarMa]

194kbps should be more than enough, even if it was stereo but I'm assuming this is mono audio so it certainly should be enough.

[redwudz]

I would open it in Audacity and see what the waveform looks like. Maybe a clipping problem? Or it's been overfiltered? A low quality microphone or impedance mismatch? Just guesses, though.

If you could post a short sample of the audio here in the same format as on the tape, that might help.

And welcome to our forums.

[greenbook]

Here's how it looks in Audacity. Not sure if this will help. It sounds boxed in throughout the whole clip. Unfortunately, I cannot provide an audio sample for you. Honestly, I wouldn't know what to do within Audacity to reduce the boxed in sound.

[netmask56]

I think you described the problem adequately by saying it was boxed in ie a small room. The acoustics are the main factor affecting the recording as others have said the technical parameters are OK. I would re-record it in a slightly larger room with adequate damping to minimise reflections or in the same room with lots of damping around her. Have abit of 'air' between her and the microphone but at the same time reasonably close. Audio processing is not going to make a significant change to the boxed in quality although a judicious amount of mid and/or high frequency boost together with a bit of low frequency cut might brighten it up and improve intelligibility.

[hello_hello]

Oddly enough I assumed the "boxed in" description meant just the opposite. Lifeless and dull due to the audio being recorded in dampened room. Of course I could be completly wrong, but if not, adding a little Reverb via Audacity's effects menu might help.

[pandy]

Anyone have a solution to this problem? Does she need to record the clip in a larger room? Does she need record at a better sample rate than 194kbps? Is there any audio editing thing I can do to reduce the "boxed in" sound?

Thanks for your assistance.

There can be few problems - i can imagine strong reverberation characteristic for a recording room - this can be fixed by recording pulse response and convolving inverted pulse response with signal.
Something like this: http://www.zynaptiq.com/unveil/ or https://acondigital.com/products/deverberate/
Another problem i can imagine is: perhaps low frequencies having to high level - i would do high pass filter from 150 - 200Hz up.

btw - if this is speech then i would advise to reduce dynamics (apply dynamic compressor).

For all processing don't use compressed audio - any recording shall be made in uncompressed/lossless compressed formats - lossy compressing is last stage after signal processing.

Reducing background noise may help also - record few second of silence before and after recording - also some slightly longer pauses during recording may help - later noise reduction can be used to reduce some background noise - i would advise to use very gentle noise reduction with relatively short fft (not more than 4096 points - better something like 2048).

https://riddlermike.wordpress.com/2013/08/25/deverb-for-free-removing-reverb-using-free-plugins/

[Cornucopia]

The truth is: we don't know specifically what you mean. As already has been shown, "boxed in" could mean any of a number of conflicting things. Too much reverb, not enough reverb, not enough HF, overly compressed/low-bitrate, comb-filtered...

We need a sample. Only way to get on the same page.

Scott

[netmask56]

Oddly enough I assumed the "boxed in" description meant just the opposite. Lifeless and dull due to the audio being recorded in dampened room. Of course I could be completly wrong, but if not, adding a little Reverb via Audacity's effects menu might help.

Too much bounce or reverb at the wrong frequencies. Not reverb as in a large undamped room.

[jagabo]

Don't use the mic built into the camera. Use an external mic up close to the person who is speaking.

[Cornucopia]

Yea, that and positioning and compression (all options on that cam compress the audio) were my hunches, but I still want a sample before giving much advice.

Scott

[jagabo]

You can run a quick test with the camera's built in mic: In the same room, put the camera about 3 inches away from the person's mouth, slightly off to the side. Make a quick recording. Sound much better? Obviously, the picture will be trash.

[julitomg]

I have the same camera model, it´s a nice camera but doesn´t have external microphone input nor headphone output. you´re stuck with the built in stereo mic or do double system sound (external recorder). The 194 kbps is the camera´s native audio quality (in both AVCHD and MP4 recording modes) Also you can´t manually ajdust the audio level, the only sound adjustments are a Wind Cut and a "Mic Zoom" (but I never use them so I don´t know how do they affect the recorded audio) If you have access to the camera, you could do some test with each setting in ON, OFF and combinations of both to see if it has anything to do with the boxy-ness (by the way, I don´t think recording in a larger room or adding reverb to the audio would help, my personal suggestion would be to first try to EQ it in Audacity )