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1. Re: mp3 vs. wave in audio-heavy projects
Captiv8r Aug 28, 2012 6:32 PM (in response to radrave)Hi there
Internally, the Captivate stores things in both WAV and MP3 formats. But when you publish, only MP3 is used, because that's the smaller and more efficient of the two.
Cheers... Rick
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2. Re: mp3 vs. wave in audio-heavy projects
radrave Aug 28, 2012 6:37 PM (in response to Captiv8r)Thanks, but that is not the issue. This is: On publishing, will captivate attempt to recompress the mp3 files? If so, that would result in some degredation of audio quality.
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3. Re: mp3 vs. wave in audio-heavy projects
Captiv8r Aug 28, 2012 7:01 PM (in response to radrave)While the rules of the game could have changed since I asked, I did once ask the dev team the following question:
Say I have an MP3 file and I import it into Captivate. I make no modifications to it and publish. Is the MP3 modified in any way?
The answer was no.
However, I also note that there are some options we have available for compression and audio sampling and such. So I'm guessing that if we elected to fiddle with these we would also run the risk of causing changes to occur when published. But only one of the development team members can conclusively answer that.
Cheers... Rick
Helpful and Handy Links
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4. Re: mp3 vs. wave in audio-heavy projects
RodWard Aug 29, 2012 12:49 AM (in response to Captiv8r)The quality of the exported MP3 audio depends largely on the Audio Quality settings you set inside Captivate. If you recorded the audio as 128 bit quality, but set the publish output quality to something under 64 bit quality, then it's quite likely that you will notice degradation in the output. I generally record at the highest setting (128bit) and output voiceover at 64bit without anyone noticing degradation. Captivate allows you to set custom output levels lower than this to try and save extra bandwidth, but the difference can then be quite noticeable.
My suggestion would be that if you have a single project file that is longer than 30 minutes, then you should certainly be breaking that project file up into multiple modules. Not only will this help your current issue but it will also likely mean you won't be coming back to this forum a little later complaining about how long your published content takes to download and users have to wait before they can see the content.
For the record, I never have project files with playing times longer than 10-15 minutes, and most of the time I try to keep them around 5-7 minutes. Modularising course content this way saves me many issues.
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5. Re: mp3 vs. wave in audio-heavy projects
radrave Aug 29, 2012 8:07 AM (in response to RodWard)Thanks Rod,
Just to clarify, when you record at 128 bit, are you referring to .wav or .mp3 files? If so, it seems that the solution you are proposing is to record in high quality wav, let Captivate do the .mp3 compression at 64 bit, and solve the project bloat problem by modularization. Correct?
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6. Re: mp3 vs. wave in audio-heavy projects
RodWard Aug 29, 2012 8:59 AM (in response to radrave)You are correct.
I record my voiceover slide by slide directly in Captivate with a good USB microphone. So I'm setting the recording quality in the Audio dialog there. Captivate records these clips as WAV files because they are uncompressed and that means no degradation of quality to start out with. If you were recording voiceover clips in another app (e.g. Sounbooth or Audition) you would also be well advised to use WAV as your output to then insert into Captivate.
When I finally publish my project, I set the sound quality for the output to 64bit because I've found voiceover doesn't need the full 128bit quality for online use. However, since I never know how many times I may want to edit or make changes to a particular clip, I play safe by at least starting out with higher than necessary quality.
This approach has always worked well for me.
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7. Re: mp3 vs. wave in audio-heavy projects
Captiv8r Aug 29, 2012 9:00 AM (in response to RodWard)Rod, you are referring to audio captured by Captivate, no?
The initial post that started the thread talked about audio that was imported into Captivate. As I understand it, that might toss a spanner or Monkey Wrench into things.
Sure would be nice to hear from one of the dev team on this! (Hint Hint)
Cheers... Rick
Helpful and Handy Links
Captivate Wish Form/Bug Reporting Form
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8. Re: mp3 vs. wave in audio-heavy projects
radrave Aug 29, 2012 9:10 AM (in response to Captiv8r)Captiv8r is correct about the original intent of the question.
The audio is not captured in captivate -- it is a lecture series. I am not the lead on this and modularization may not be possible. I simply want to confirm that if we convert the audio to the smallest possible acceptable mp3 size first, then import in to Captivate and perhaps map the publish settings to those existing in the mp3 files, that Captivate will not attempt to recompress the files.
Dev team please chime in on this. Thanks!
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9. Re: mp3 vs. wave in audio-heavy projects
RodWard Aug 29, 2012 9:10 AM (in response to Captiv8r)Rick, yes I realise that the original post was talking about importing audio, rather than recording it in Captivate. But in doing it both ways I haven't found it made much difference to the end quality. The main points are that you start with the highest quality and then publish out to whatever you need. Starting with low quality can only mean you go downhill from there with no way back if you find that after some sound edits you can no longer match the quality of the audio in the rest of the project file.
Overall I've found that Captivate's sound recording feature works quite well quality wise. I used to record audio separately and then import as WAVs. But for years now I've just recorded directly in Captivate and only used higher end audio tools (Soundbooth or Audition) to correct some general issue or introduce special effects.
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10. Re: mp3 vs. wave in audio-heavy projects
radrave Aug 29, 2012 9:18 AM (in response to RodWard)Thanks Rod,
As a videographer as well as an ID I'm familiar with the need to start with the highest quality before compression, and that each additional compression degrades audio quality somewhat. No one is suggesting generating only mp3 files -- there would always be a .wav backup if further editing were required. That is the question I am trying to answer. Does Captivate recompress automatically, or will it leave well enough alone assuming the publish settings match?
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11. Re: mp3 vs. wave in audio-heavy projects
radrave Sep 2, 2012 4:32 PM (in response to radrave)Still waiting for the Dev team to answer this question . . .
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12. Re: mp3 vs. wave in audio-heavy projects
Ashish-CaptivateTeam Sep 3, 2012 2:21 AM (in response to radrave)If you import MP3 files in Captivate and do not edit them, then the original MP3 files will be used in published content. The decompress-recompress cycle will not be invoked in this case.
Hope this helps,
Ashish from Adobe Captivate Team
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13. Re: mp3 vs. wave in audio-heavy projects
rgcunningham Jan 3, 2013 11:18 AM (in response to Ashish-CaptivateTeam)Thanks for that clarification, Ashish. But something Rod said raises a question for me. As Rod does, I record my audio directly in Captivate. As I understand this thread, Captivate, as a result, creates a WAV file to store my audio. But can I control the quality of the recorded WAV file that Captivate creates? From what I see in the Library of my projects, all audio that I record directly in Captivate is recorded at very, very high quality --- 705 kbps, 44 kHz. And this, then, is compressed into mp3 when I publish, based on my selection in the Audio Settings dialog. It does not appear that the Audio Settings dialog has any effect at all on the recorded WAV file, only on the published mp3 in the output.
Am I all wet, or what?
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14. Re: mp3 vs. wave in audio-heavy projects
Ashish-CaptivateTeam Jan 3, 2013 9:37 PM (in response to rgcunningham)Hi, Captivate records the audio at a pre-defined settings (44.1 KHz, 16-bits). This is kept only in CPTX file. This enables Captivate to provide smooth editing experience and exporting/publishing at the user defined values.
Hope this helps,
Ashish
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15. Re: mp3 vs. wave in audio-heavy projects
SethXP Jan 3, 2013 9:47 PM (in response to Ashish-CaptivateTeam)Ashish,
The only reason CP records audio at a pre-defined setting is because MP3 doesn't support higher bitrates.It has nothing to do with providing smooth editing experience.
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16. Re: mp3 vs. wave in audio-heavy projects
Ashish-CaptivateTeam Jan 3, 2013 9:58 PM (in response to SethXP)What I meant by "editing experience" is that MP3 files cannot be edited directly, so Captivate keeps it in a form that is closer to PCM. By "smooth" I meant that by keeping it at a standard setting, we remove many complexities that may arise in editing workflow.
Ashish
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17. Re: mp3 vs. wave in audio-heavy projects
RodWard Jan 3, 2013 10:15 PM (in response to Ashish-CaptivateTeam)Now that we've opened this can'o'worms about audio in Captivate, something I've been dying to ask for ages is:
How are we to ACTUALLY understand that bitrate of 700 or more kilobits per second? Is that legit? It seems inordinately high.
And when the Audio Settings dialog is set at CD Bitrate quality or 128 kbps, is that ONLY referring to what the OUTPUT MP3 will be published at, or does it also in any way affect the recording quality level? I'm asking because in past versions of Captivate I had found that if I set the quality there to say 64kbps when recording, and also published with this same setting, then the resulting MP3 audio output was a bit "whooshy". Whereas if I recorded at 128kbps and then published at 64kbps the output audio was fine.
So, is the Audio Settings dialog Bitrate level controlling the recording, publishing, or both outputs?
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18. Re: mp3 vs. wave in audio-heavy projects
SethXP Jan 3, 2013 11:33 PM (in response to RodWard)Rod,
This is truly a can of worms you so aptly put, but the rule of thumb is to record at the highest setting and let CP do its job converting to a lossy mp3 (mpeg-2.5 audio layer 3, if I'm not mistaken). User defined settings control the input (recording) and not the compressed output. However, remember GIGO (garbage in garbage out). The way the mp3 compression works is to pick out the weakest signal to make the file lighter. Best advice, stick to what works.
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19. Re: mp3 vs. wave in audio-heavy projects
Ashish-CaptivateTeam Jan 3, 2013 11:33 PM (in response to RodWard)Hi Rod,
Let me try to explain it -
When we record, then only two parameters are important -
Sampling Frequency - the number of times the analog audio wave will be sampled per second for digital conversion. This is set at 44.1 KHz or 44100 times a second for Captivate and this is not configurable.
Bits per sample - How many bits will be used to store the Sample data. For Captivate, it is 16-bits.
So, for one second of Audio, you will get 44100 * 16 = 705600 bits
This is uncompressed data and hence if you have to play it, it will become 705600 bits / second or what you see as 705 kbps. This raw form allows us to edit the audio and publish with different data rates.
However, when we publish, we encode this for MP3 and there the data rate used is 128 kbps, so the encoder will take the raw data and give you an audio file that will have the data rate that you specified in the Audio Settings.
Finally, Audio Settings apply only to the published audio. Internally, in Captivate Audio is kept in raw form (ideally, near raw form as it is compressed to reduce size of CPTX file). When you publish, then the data rate from Audio Settings is taken and MP3 is produced with that data rate.
Hope it clarifies,
Ashish
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20. Re: mp3 vs. wave in audio-heavy projects
RodWard Jan 3, 2013 11:56 PM (in response to Ashish-CaptivateTeam)Thanks Ashish. That's very helpful information. Much obliged!
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21. Re: mp3 vs. wave in audio-heavy projects
rgcunningham Jan 4, 2013 5:10 AM (in response to Ashish-CaptivateTeam)Thanks very much Ashish. That confirms what I thought, and supports my experimentation results as well.





