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Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 5:06 pm
Posted by nckhrs
Hi,

I work with several mono WAV files, they are pretty long (2 - 3 hours). They have stereo channel (L and R track), however, the audio is only on the left channel.
I want to make the audio to play on both L and R channel, and here is what I did:

1. Split Stereo Track.
2. Select the whole left channel.
3. Paste it into the right channel.
4. Export Audio (into a new WAV file).

Everything looked fine on Audacity, I got full length audio on both L and R (approximately 2 hour and 30 min).
However, when I tried to play it using WMP, it showed that the file is only 1 hour and 42 min long. :o
So, I opened it using Audacity, to my surprise, the audio only appear up to 1 hour 42 min. The rest are blank (on both channels). :(

Anybody experience similar problem?
Did I do something wrong?

I really appreciate your help. :)

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 5:32 pm
Posted by steve
I'm not sure what went wrong, but there's a much easier way to make a single channel stereo recording play through both L and R channels:
1) Split to Mono
2) Delete the empty track (click on the [X] in the top left corner of the track.

That's all. it will play through both L and R channels.
When exported, it will create a mono track that plays through L and R channels.

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 6:13 pm
Posted by nckhrs
steve wrote:I'm not sure what went wrong, but there's a much easier way to make a single channel stereo recording play through both L and R channels:
1) Split to Mono
2) Delete the empty track (click on the [X] in the top left corner of the track.

That's all. it will play through both L and R channels.
When exported, it will create a mono track that plays through L and R channels.


Thanks a lot Steve, I will give it a shot. :)

Btw, just out of curiosity, it looks like it may be related to 4GB limitation.
Original file is 3GB (left only), and it became 6GB after I copy pasted the audio to the right channel.
Now... 1h 42m is approximately 2/3 of 2h 30m, which correlate with the size (4GB is 2/3 of 6GB).
Could it be related? Once again... this is just my curiosity.

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 6:35 pm
Posted by kozikowski
The unconditional WAV file limit is 2Gb which works out to stereo 3 hours. Some systems can deal with 4Gb. Nobody can deal with 6Gb. You can get away with nose-bleed high quality MP3 or some of the other formats.

Koz

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 7:27 pm
Posted by steve
kozikowski wrote:Some systems can deal with 4Gb

Are there any computers of the last 20 years that don't?
I've not seen the problem occur below 4GB in the last decade.

For a standard WAV file, the 4GB limit is absolute - data beyond 4GB cannot be accessed. Very often, exceeding 4GB will corrupt the file.

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 7:34 pm
Posted by DVDdoug
Original file is 3GB (left only), and it became 6GB after I copy pasted the audio to the right channel.
Yup! Twice the uncompressed data.

If you actually have a 6GB file you should be able to open it in Audacity as Raw data. Then export in a different format or in a different resolution. (It's the 32-bit file-size field in the WAV header that has overflowed and reporting the wrong size.)

FYI - "CD quality" (44.1kHz, 16-bit, stereo) is about 10MB per minute.

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 8:31 pm
Posted by nckhrs
steve wrote:
kozikowski wrote:Some systems can deal with 4Gb

Are there any computers of the last 20 years that don't?
I've not seen the problem occur below 4GB in the last decade.

For a standard WAV file, the 4GB limit is absolute - data beyond 4GB cannot be accessed. Very often, exceeding 4GB will corrupt the file.


Thanks Steve, I didn't know WAV file has 4GB hard limit.

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 8:41 pm
Posted by nckhrs
DVDdoug wrote:
If you actually have a 6GB file you should be able to open it in Audacity as Raw data. Then export in a different format or in a different resolution. (It's the 32-bit file-size field in the WAV header that has overflowed and reporting the wrong size.)


That's the thing. It would work if the original file is 6GB. (Btw, but what are other raw formats that don't have 32-bit file-size limitation? :?: )
However, my original file is 3GB, and then after I worked on it, it became 6GB (still looked OK in Audacity), saved it, and then it got corrupted (because of WAV 4GB limit). Yep... supposedly after I worked on it, I need to export it to other format (MP3 for example) to avoid saving 6GB WAV file.

Note: I will try and stick Steve's suggestion to save it as Mono (smaller size) for practical reason.

Thanks a lot! :)

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Mon Dec 04, 2017 10:45 pm
Posted by DVDdoug
That's the thing. It would work if the original file is 6GB.
No, 6GB is not a valid WAV file.

(Btw, but what are other raw formats that don't have 32-bit file-size limitation? :?: )
Almost any other format. RAW PCM data generally terrible because you (or the application) has to know the sample-rate, bit-depth, number of channels, the endian, and a couple of other details that are normally specified in the audio file header and read automatically by the application. You can use raw audio data in a "contained" application such as a game or a automated telephone system where there's only one format and one application and the application knows the format in advance.

What format do you want and/or what are you going to do with the file? I assume you are currently using "high resolution" (greater than 44.1kHz and/or greater than 16-bits)? There's probably no reason for that since CD quality is better than human hearing.

FLAC is lossless compression, there is no file-size limit, and the files are about half the size of WAV. MP3 is lossy compression, but at higher bitrates it often sounds identical to the uncompressed original (in a proper blind listening test). A good quality MP3 is about 1/5th the size of a CD quality file and if you start with high-resolution it might be 1/10 the size, or smaller.


P.S
I didn't read carefully before and I'm confused about something -
I work with several mono WAV files, they are pretty long (2 - 3 hours). They have stereo channel (L and R track), however, the audio is only on the left channel.
I want to make the audio to play on both L and R channel, and here is what I did:

1. Split Stereo Track.
2. Select the whole left channel.
3. Paste it into the right channel.
4. Export Audio (into a new WAV file).
A stereo WAV file with one silent channel is the same size as if there is sound in both channels. In WAV file, silence takes-up just as much space as non-silence. (A regular 1-channel mono file is half the size.) So... Something else was changed... Maybe you increased the bit-depth?

Re: Lost audio end part when converting from Mono to Stereo

Permanent link to this postPosted: Tue Dec 05, 2017 2:49 am
Posted by nckhrs
DVDdoug wrote:P.S
I didn't read carefully before and I'm confused about something
A stereo WAV file with one silent channel is the same size as if there is sound in both channels. In WAV file, silence takes-up just as much space as non-silence. (A regular 1-channel mono file is half the size.) So... Something else was changed... Maybe you increased the bit-depth?


Thank you for such wealth of info.

Hmmm... that's quite interesting with the size thing. I didn't change anything.
I just opened the file with Audacity, and it shows the stereo track with only the signal/audio on the left channel, and it also says 32-bit float.
So... I'm not sure either how the size double when I copy paste the left to right. Did I do something wrong during my copy paste operation?