Recorded audio sounds slow

scottbomb · December 14, 2013, 12:11am

I’ve been using Audacity to record streaming audio for years and now all of a sudden, with no changes to the settings, the audio is at a lower pitch and playback sounds slower than normal. Imagine recording something with a cassette recorder and then playing it back with the motor going slightly slower. That’s the sound. Very annoying.

Specs: Kubuntu 13.10 with Audacity 2.0.3, downloaded from the Ubuntu repo. I removed and re-installed it the other day and that seemed to have “fixed” the problem, until today. Today’s recording session sounds exactly like it did the other day.

Any ideas?

kozikowski · December 14, 2013, 7:55am

That’s scary. We can whip out reasons for the show to speed up. Slowing it down is harder. Do older shows sound slow as well? If you play a ten second clip, does it take ten seconds?

Koz

steve · December 14, 2013, 3:52pm

In “Edit > Preferences > Quality”, what is the “Default sample rate”?
Try both 44100 and 48000 to see if it makes a difference.

scottbomb · December 17, 2013, 5:55am

Sample rate is 44,100 Hz. I ran the same operation today and it recorded fine with no quality issue. It may be intermittent. Will report back in a few days.

dfbarbour · March 1, 2014, 5:27am

scottbomb did you ever figure out what the issue was? I have had this problem intermittantly. Now it seems to be permanently broken. Playbacks of recorded streams sound slow.

Gale_Andrews · March 1, 2014, 5:45pm

Scottbomb is very unlikely to still be reading or following this.

Please give us the required information to go on (see the pink panel at the top of the page).

Also exactly what browser are you playing the audio in and exactly how are you recording that in Audacity?

Gale

dfbarbour · March 2, 2014, 12:31am

Linux 3.5.0-17-generic i386
distro: Linux Mint 14, fully updated
Audacity 2.0.6-alpha-Feb 24 2014 installed through Software Manager
Pulse Audio volume control installed.

I was able last night to record from a streaming video after uninstalling Audacity, shutting down, restarting and reinstalling Audacity. However, I had tried this before without success, and indeed, the slow playback resumed on my next attempt to record audio from another video stream. I tried uninstalling, shutting down and reinstalling again, but the slowness continued. I had already experimented extensively with changing sample rates, quality, dither, etc., in Audacity’s Preferences. Just for the hell of it, I tried changing Default View Mode from “Waveform” to “Spectrogram”. Lo and behold, recording was now normal! I switched back to “Waveform” and the fix persisted. Today I started the computer from Sleep, and went back to try to record from the same stream I’d finally had success with yesterday. Again, the slow playback. So I tried setting Default View Mode to “Spectrogram” and again Audacity started recorded normally. Set it back to “Waveform” and tried recording again, and everything still seemed normal. Closed Audacity and restarted it. Again the slow behavior. Switched to Spectrogram, still slow. Switched back to Waveform, and everything normal again. I have tried this a number of times, and usually, switching the Default View Mode will fix the problem for the current session with the slowness returning again when I restart Audacity.

I still don’t know what is causing the slow-sounding recording. There is a noticable pitch decrease of maybe 10% or so. This seems to correspond to the ratio between 48000 and 44100, but that could just be a coincidence.

In the past, I seemed to be able to prevent the slowness by starting the video stream before starting Audacity. This no longer works.

Gale_Andrews · March 2, 2014, 1:38am

And, what browser or tool is playing the audio, and exactly how are you recording it in Audacity?

Please post the information from Help > Audio Device Info… .

Are the recorded tracks the same length irrespective of whether they play back correctly or too slow? Or is the slow track longer than it should be for the length that you recorded?

Gale

dfbarbour · March 2, 2014, 3:52pm

browser: Firefox 27.0.1 (Firefox for Mint 1.0)

pulse Volume Control > Recording > Alsa capture from: Monitor of Built-in Analog Stereo

Audacity settings:
Audio Host: ALSA
Output Device: pulse
Input Device: pulse: line:0
Input Channels: 1 (Mono) Input Channel

Audacity > Edit > Preferences > Quality
Default Sample Rate: 44100
Default Sample Format: 32-bit float
Real Time Conversion
Sample Rate Converter: High Quality
Dither: None
High Quality Conversion
Sample Rate Converter: High Quality
Dither: Shaped

Audacity > Help > Audio Device Info

=============================
Default capture device number: 10
Default playback device number: 10
==============================
Device ID: 0
Device name: HDA Intel: ALC662 rev1 Analog (hw:0,0)
Host name: ALSA
Input channels: 2
Output channels: 2
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
==============================
Device ID: 1
Device name: HDA Intel: ALC662 rev1 Analog (hw:0,2)
Host name: ALSA
Input channels: 2
Output channels: 0
Low Input Latency: 0.011610
Low Output Latency: -1.000000
High Input Latency: 0.046440
High Output Latency: -1.000000
Supported Rates:
==============================
Device ID: 2
Device name: HD Pro Webcam C920: USB Audio (hw:1,0)
Host name: ALSA
Input channels: 2
Output channels: 0
Low Input Latency: 0.016000
Low Output Latency: -1.000000
High Input Latency: 0.064000
High Output Latency: -1.000000
Supported Rates:
==============================
Device ID: 3
Device name: sysdefault
Host name: ALSA
Input channels: 128
Output channels: 128
Low Input Latency: 0.042653
Low Output Latency: 0.042653
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    8000
    9600
    11025
    16000
    22050
    32000
    44100
    48000
    88200
    176400
==============================
Device ID: 4
Device name: front
Host name: ALSA
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
==============================
Device ID: 5
Device name: surround40
Host name: ALSA
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
==============================
Device ID: 6
Device name: surround51
Host name: ALSA
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
==============================
Device ID: 7
Device name: surround71
Host name: ALSA
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
==============================
Device ID: 8
Device name: pulse
Host name: ALSA
Input channels: 32
Output channels: 32
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    8000
    9600
    11025
    12000
    15000
    16000
    22050
    24000
    32000
    44100
    48000
    88200
    96000
    176400
    192000
==============================
Device ID: 9
Device name: dmix
Host name: ALSA
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.042667
High Input Latency: -1.000000
High Output Latency: 0.042667
Supported Rates:
    48000
==============================
Device ID: 10
Device name: default
Host name: ALSA
Input channels: 32
Output channels: 32
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    8000
    9600
    11025
    12000
    15000
    16000
    22050
    24000
    32000
    44100
    48000
    88200
    96000
    176400
    192000
==============================
Selected capture device: 8 - pulse
Selected playback device: 8 - pulse
Supported Rates:
    8000
    9600
    11025
    12000
    15000
    16000
    22050
    24000
    32000
    44100
    48000
    88200
    96000
    176400
    192000
==============================
Available mixers:
==============================
Available capture sources:
0 - Mic:0
1 - Line:0
2 - Mic:1
3 - Line:1
==============================
Available playback volumes:
0 - Master:0
1 - Headphone:0
2 - Speaker:0
3 - PCM:0
4 - Line:0
5 - Mic:0
6 - Mic Boost:0
==============================
Capture volume is native
Playback volume is native

Gale_Andrews · March 2, 2014, 4:31pm

Have you tried setting Audacity to record in stereo?

Also:

Gale

dfbarbour · March 2, 2014, 5:59pm

Are the recorded tracks the same length irrespective of whether they play back correctly or too slow? Or is the slow track longer than it should be for the length that you recorded?

Slow track:
One minute (1:00) of stream = approx. 1:06 Audacity recording

When playback is correct:
1:00 = 1:00

Here are some interesting twists:

YouTube (Flash) streams now always seem to record correctly, although I have had problems with other Flash streams in the past.
When a Firefox tab is open containing a YouTube video I have played from, the tab which contains the problem (Vimeo) stream now records correctly.
When recording a Vimeo stream, Edit > Undo Record fails to remove the track as it ordinarily does after a single take.
After running Tracks > Remove Tracks after a slow Vimeo take, recording returns to normal speed, however, Edit > Undo Record still fails to remove the track.

The problem seems to be with Vimeo. Here is an example of the problem video: http://www.premrawat.com/category/updates/

A workaround is: 1. Record a slow take, 2. Tracks > Remove Tracks, 3. start recording and restart the stream. (However, Edit > Undo Record still fails to remove the track.)

dfbarbour · March 2, 2014, 6:05pm

Have you tried setting Audacity to record in stereo?

Recording in stereo has no effect, i.e., slow recording persists.

Gale_Andrews · March 4, 2014, 4:46am

OK so it is a recording problem presumably when the playback rate of the video differs. If so you will never be able to predict it in advance.

Steve has suggested before that pulseaudio volume control should take care of these problems but he would have to advise you how to configure it to do this.

The obvious solution is to download the videos ( https://vimeo.com/help/faq/sharing-videos/downloading-videos ) or unofficial solutions (see Google).

I have no idea how you managed to do that. What menu item or button do you use to record?

Gale

dfbarbour · March 4, 2014, 8:57pm

What menu item or button do you use to record?

I click on the Record button (red circle button)

Update:
My workaround did not work today. However, I discovered another possible workaround:

Open a Firefox tab and play a YouTube (Flash) video. Leave the tab open.
Go to the Firefox tab that contains the Vimeo video. Play the Vimeo stream and record the audio normally with Audacity.

For some reason, if a Flash video was previously playing in another Firefox tab, and the tab is left open, Audacity will then record at the correct speed from the Vimeo stream.

The obvious solution is to download the videos ( > Vimeo Help Center > … ing-videos )

This is not an option. The Vimeo player on the site I am trying to record the audio from does not have a download button. (http://www.premrawat.com/category/updates/)

steve · March 4, 2014, 10:01pm

This will probably not solve the problem, but the first thing that I would do would be to set “Real Time Conversion > Sample Rate Converter: Medium Quality”.
Since Audacity’s resampling library was updated, even “Medium Quality” is very good, and going down from “High Quality” to “Medium” is a lot less demanding on your computer. This will not adversely effect the quality of the recording, it just slightly reduces the resampling quality if Audacity needs to convert sample rates on the fly. Exporting and mixing down use the High Quality Conversion settings.

Regarding the problem, this does not sound like an Audacity problem. I think it is almost certainly somewhere between Firefox, whatever plug-in is playing the media, and PulseAudio.

A common issue when playing media in a web browser (though not generally a “problem”) is that the ports into PulseAudio are not closed properly when the video stops. I suspect that this is related to the problem that you are experiencing. The change in speed and pitch (with no mention of stuttering or rapid clicking) does sound like a sample rate mismatch.

If, as I suspect, the problem is in this area, then we are probably not going to be able to “fix” this problem but hopefully find a practical “solution” (aka “workaround”).

That’s probably because the copyright holder does not want you to copy it.
Nevertheless, assuming that you have obtained the legal rights to copy this content, I find that “FlashGot” (not to be confused with “FlashGet”) Firefox plug-in works with most on-line video content.

Gale_Andrews · March 4, 2014, 10:05pm

That is possible - I understand Firefox uses Flash for Vimeo videos.

It’s also possible that if the previously playing video played at the wrong speed then the Vimeo stream loaded in the same tab would record at the wrong speed.

Or… it all depends on the original video.

Is your Firefox Flash plug-in up-to-date?

Another thing you could try is use a browser that uses HTML5 for Vimeo videos instead of Flash.

Of course it’s an option. I can download any Vimeo video at will - download button or not. Use your favourite search engine for unofficial solutions, or try Steve’s suggestion.

Gale

dfbarbour · March 5, 2014, 2:24am

Thanks, Gale and Steve!

gbell12 · October 7, 2015, 10:09pm

For any future Googlers…

The workaround is to record at 44.1 kHz (Project rate 44100 in the lower left of the window, then start recording).

The resulting track will be at 44.1 kHz. Use the little pulldown on the track next to the text “Audio Track”, then Set Rate, then set the rate to 48.0 kHz.

Playback and resulting exported MP3 file will be the correct pitch/speed.

This is for Audacity 2.0.5 on Ubuntu 14.04.1 with Pulseaudio active and working, but the “Audio Host” in Audacity set to ALSA, recording something playing back in Firefox.

rebelwriteruk · October 18, 2015, 9:10pm

I’d Like to thank gbell12 for the workaround, it’s certainly cured my frustrations, this happened every time I recorded anything be it a radio stream, voice recording, or a file on my hdd. Everything was recording at around 10% quicker resulting in around a 10% slower playback, I even resorted to running Audacity in wine (which actually recorded fine) but the trade off was I had to save as .wav then open the file in my native Audacity version to convert into my preferred file format. so thanks yet again to gbell12 for the workaround

Gale_Andrews · October 18, 2015, 11:04pm

Yes thanks to gbell12 indeed for contributing.

However do note that the solution of changing project rate is not foolproof and has just as often been reported not to work (or only to work sometimes) which is probably why none of us mentioned it.

Assuming you are choosing the pulse device to record from in Audacity, pulse should be able to handle the conversions without speed changes. But if that handling does not work and for example you have a 44100 Hz only device and the stream is 48000 Hz, you may see the problem you describe.

Gale