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Topic: optimizing podcasts for listening in car (Read 3341 times) previous topic - next topic
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optimizing podcasts for listening in car

I'm experimenting with trying to make podcasts more listenable in the noisy environment of an automobile. Here's what I'm doing so far in foobar's converter:

Dynamic compression using George Yohng's W1 Limiter with settings:
Threshold: -20.0dB
Ceiling: -10.5dB (still experimenting with this setting)
Release: 200ms

EQ: a low-cut curve starting at -20dB at 55Hz and gradually increasing to 0dB at 622Hz

Next I will probably also normalize using ReplayGain or MP3Gain. Should I apply this after transcoding or before? Or should I use the ReplyGain processing function WITHIN the converter?

99% of these podcasts are download from the web and are in 64 kbps, MP3/CBR format. I'm transcoding them to MP3 VBR V3 (LAME) in the converter.

I need help with all of this, so I'm open to suggestions. Thanks!

optimizing podcasts for listening in car

Reply #1 –
Quote from: toronado455 on
99% of these podcasts are download from the web and are in 64 kbps, MP3/CBR format. I'm transcoding them to MP3 VBR V3 (LAME) in the converter. I need help with all of this, so I'm open to suggestions. Thanks!

The quality of your original files is 64 kbps, MP3 only (genre = talk?). Recompressing this files again into a lossy format would reduce audio quality furthermore. Can you play any lossless format in your car to avoid this?

Search the forum for the DSP "VLevel". Maybe it would be enough audio processing for your purposes (listening in a noisy car environment without the need of adjusting the volume too frequently).

This is HA. Not the Jerry Springer Show.

optimizing podcasts for listening in car

Reply #2 –
Thanks, I tried VLevel at first but I think I like George Yohng's W1 Limiter better. I might try VLevel again, but I just don't think it gives as much compression.

The genre is talk, and I'm using the MP3 file player in a Garmin nuvi660 portable NAV unit feeding through an FM modulator into my car's factory stereo, so there is so much opportunity for degradation in that chain already that I think VBR V3 isn't really harming anything further, right?

Also, I've just discovered that the Garmin doesn't recognize ReplayGain tags. So that means I'm going to be using MP3Gain to normalize instead of foobar. Should I apply MP3Gain before or after DSP processing in foobar? (After is what I'm doing now.)

EDIT: I suppose I could use ReplayGain processing in the converter since it actually changes the audio data (not just tags)? Would that be better than MP3Gain?

optimizing podcasts for listening in car

Reply #3 –
Quote from: toronado455 on
I might try VLevel again, but I just don't think it gives as much compression.

toronado455,

your ReplayGain-questions should be answered by other forum members.

If the use of ReplayGain should not be possible in your specific case you can try Kjaerhus Audio Classic Master Limiter. It should give you enough compression.

Robertina.
This is HA. Not the Jerry Springer Show.

optimizing podcasts for listening in car

Reply #4 –
Thanks for the links to the Kjaerhus plug-ins. I tried both the Classic Master Limiter and the Classic Compressor, but I found that neither of those were anywhere near as effective as George Yohng's W1 Limiter when compressing speech in podcasts. VLevel is probably better for music because it gradually ramps up and ramps down. George Yohng's W1 Limiter works best for me on these podcasts.

optimizing podcasts for listening in car

Reply #5 –
If you are in a noisy environment AND the audio loudness is very dynamic (you have pretty silent and loud parts?): VLevel dsp will help you, because it permanently corrects the volume.

Replaygain: Not surprising, rg tags are supported close to nowhere.

optimizing podcasts for listening in car

Reply #6 –
Quote from: toronado455 on
The genre is talk, and I'm using the MP3 file player in a Garmin nuvi660 portable NAV unit feeding through an FM modulator into my car's factory stereo, so there is so much opportunity for degradation in that chain already that I think VBR V3 isn't really harming anything further, right?
You are right. Although you lose some quality, VBR V3 is rather an overkill (it should have average bitrate 175 kbps). V 7 or V 8 could be enough. Just try it if the disk space or a battery life is important.

Quote from: toronado455 on
Also, I've just discovered that the Garmin doesn't recognize ReplayGain tags. So that means I'm going to be using MP3Gain to normalize instead of foobar. Should I apply MP3Gain before or after DSP processing in foobar? (After is what I'm doing now.)
Definitely after all the DSP processing. Replay Gain should be computed for the audio intended to be played.

Quote from: toronado455 on
EDIT: I suppose I could use ReplayGain processing in the converter since it actually changes the audio data (not just tags)? Would that be better than MP3Gain?
Yes, the Replay Gain processing in the converter really changes the audio data. The result should be virtually the same as with MP3Gain.

Notice also that doing just dynamic range compression without Replay Gain could be sufficient because the compression already normalizes the audio. Additional Replay Gain could do a more exact normalization because it uses a psychoacoustic model.
 

optimizing podcasts for listening in car

Reply #7 –
Quote from: pabouk on
You are right. Although you lose some quality, VBR V3 is rather an overkill (it should have average bitrate 175 kbps). V 7 or V 8 could be enough. Just try it if the disk space or a battery life is important.
Wow, OK. V 8 is getting pretty low. I suppose it's all relative, though. Disk space hasn't been a problem yet though. I've never maxed my 2GB SD card yet, and my Garmin will take up to a 32GB card I think. Plus these are mono files, so it's like half the data.

Quote from: pabouk on
Definitely after all the DSP processing. Replay Gain should be computed for the audio intended to be played.
OK. Is it OK to use the converter for both DSP and RG at the same time (during the same conversion)?

Quote from: pabouk on
Yes, the Replay Gain processing in the converter really changes the audio data. The result should be virtually the same as with MP3Gain.
OK. I've not had any luck getting the RG processing in the converter to work - either separately or together with DSP. I've got it selected and everything, it just doesn't apply any change to the audio in the conversion process. I don't know what I'm doing wrong there. I even created a test file that peaks at -30dB and run it though and no change at all. And RG track scan on files both before and after processing shows exactly the same result.

EDIT: OK, I figured it out. The converter will not apply any audio adjustment to files unless RG tags have been set for the file.

Quote from: pabouk on
Notice also that doing just dynamic range compression without Replay Gain could be sufficient because the compression already normalizes the audio. Additional Replay Gain could do a more exact normalization because it uses a psychoacoustic model.
Yes. I've noticed this. I don't really need to apply RG after compression with W1 because the compression pretty much normalizes everything anyway.

One other note about MP3Gain vs. Replay Gain... With MP3Gain, the minimum adjustment it can make is plus or minus 1.5dB. So it leaves almost all the files untouched because after compression, the adjustments that would need to be made are mostly smaller than + or - 1.5dB.