After editing, exporting does not save changes

[tovaria]

Hello,
I am still quite new to Audacity. I was trying to find an answer to my question on the forum but I did could not.
So my problem is that I load an mp3 in Audacity. I use the time shift tool to make the file 10 seconds longer to match the video. Then I try to export as mp3 but somehow my changes are not saved. The file has still the original lenght. I tried it several times and it never works.
What do I do wrong? Is there a different way to achieve this?
Thanks for your help
tovaria

[steve]

I'm not quite clear about what you are trying to do - are you wanting 10 seconds of silence at the beginning of the mp3?

[tovaria]

no, im trying to "stretch" the file... is this not what this time shift tool does?

[kozikowski]

<<<is this not what this time shift tool does?>>>

No. Time Shift moves all parts of a file sooner or later in time.

You want Effect > Change Speed, Change Tempo, etc.

Koz

[tovaria]

My problem is that I want to add a new audio track to a movie (another language). The movie is 1:54:29 long but my sound is only 1:54:18 as it comes from a PAL DVD, not NTSC. This was they are not in sync (at the beginning yes, but later it gets more and more apart).
What effect should i use to get the same lenght for the sound? Can you please help? I already spent two days trying.
Thanks

[george13]

You can change the sampling rate to a lower number, so that the audio is stretched. With every track there is a pull-down menu where you can change it ("set rate" then "other"). In your case (assuming that the original sample rate is 48000 as mostly with movies) that would be 6858 (seconds) / 6869 (seconds) * 48000 = about 47923. Then simply export.

[tovaria]

thank you. I will try this option. So far I tried "change speed", which solved the problem with the lenght but the audio quality got much weaker. Is this normal?
I will try what you suggested.
Thanks again

[george13]

Hi,

I just tried 'change speed' with a piece of music and couldn't hear the sound getting much worse.

Maybe you exported as a low bitrate mp3?

What is your final video format? I would make sure that the audio is only re-compressed once in the process; like export as 160 kbit/s mp3 and then use something like 'ffmpeg -i movie.avi -i movie.mp3 -acodec copy -vcodec copy movie2.avi'. Or you could export as uncompressed wav and let the program you use for combining the audio and video do the compressing of the audio.

[tovaria]

I have the video in avi or dvd format. I made the avi so that I can experiment around more with a smaller size. But my original idea was to give a second audio track to the dvd format.
I need to read a bit more about these codecs, as this does not say much to me at the moment.
I thought this would be easier

Thanks for the help.

[steve]

So far I tried "change speed", which solved the problem with the lenght but the audio quality got much weaker.

The sound quality should be virtually unaffected by the "change speed" effect, however there will be some change in the pitch as well as the tempo. For your purpose this is not a problem.

Any loss in sound quality that you are experiencing is likely to be a result of the compressed formats that you are using.

The sound quality on DVDs is usually very good, but it is encoded within VOB files.
Your task involves extracting the sound from the video, then editing it, then putting it back into the video. Ideally you should use a DVD ripper program to extract the audio and convert it to WAV format. You can then edit it in Audacity, Export the processed sound as a WAV, then use your video software to put the WAV file together with the video.

For DVDs that are not copy protected you can use SUPER by erightsoft to convert the audio stream of a VOB files to WAV format. For commercial DVDs the process is rather more complicated, but you may find some help on the Doom9 website. Once you have the WAV file, the audio processing will be almost lossless, and virtually all video editors support WAV files.

The formats used for videos and DVDs can be very complicated. This is a good website for information about working with DVDs http://www.doom9.org/