Why are do we have MP3's with a VBR, whats the point?
VBR encoded MP3's are generally smaller than standard MP3s of the same sound quality and generally sound better, especially in the high frequencies it's also great for spoken word audio as there are often pauses and silence between sentences. However most MP3 players especially the decoders on standalone DVD players with DivX support will exhibit progressive audio delay errors with VBR audio of any type.
If you open an AVI with VBR audio MP3 track in VirtualDub or VirtualDubMod it will give you this WARNING that you may experience progressive audio errors this is certainly the case especially if you want to convert your downloaded DivX Stage 6 into DVD format that use CBR audio in either LPCM or AC3
You will need to download the
Lame ACM MP3 codec extract it to a temp folder then right click on LameACM.inf, and choose install this will register and install the ACM for use with VirtualDub and VirtualDubMod note you can do this without the ACM package there is also an
AC3 ACM codec that you might as well install at the same time this will allow VirtualDub to decompress Dolby Digital 5.1 audio streams.
PROCEDURE ONE:
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Convert using an ACM or audio compression manager for the required MP3 codec use the same one that Gspot tells you that has been used either LAME or
- Open Virtualdub, open your video then select Direct Stream Copy from the audio menu tick full processing mode, and then choose audio compression. The Lame MP3 should show up in the left-hand list choose CBR stereo on the right.
- It a good idea to look in the file information so that you make sure to choose the same sample frequency as the original VBR MP3 in this case its 48,000Hz you don't want to re-sample it it will take extra time
This screendump shows the original XVID @ bitrate of 979 kbps with a 154kbps VBR audio MP3 and sample rate of 48KHz this will not work on most standalone DVD
This screendump shows the AVI re-encoded to DivX iwth a fourcc of DX50 @ bitrate of 1,000 kbps with a 128kbps CBR audio MP3 and sample rate of 48KHz this will not work on all DivX certified DVD players the pixel aspect is also 720x576.
The framerate has also been converted (NOT CHANGED) from FILM 23.976 to the UK standard of PAL 25fps you can't adjust it it must be done on the lower section of the window.
PROCEDURE TWO:
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Use
AVIDemux v2.52 or the latest beta
AVIDemux to do the whole process for you it will create a VBR timemap to keep the AV in synch without it forget it !!!
It also allows you to convert the audio using the LAME ACM MP3 and convert to to a CBR it should take about 15mins for a 350MB AVI file don't forget to keep the AVI container packed Video bitstream to give the best re-encoding results to give you the OpenDML AVI v2.0
I have used this with mixed results it is definitely the easiest to use option with a great GUI it just takes a while to know which buttons to press to give the required results, you can also set a time lag/lead for fixed audio problems and increase the audio volume in (dB) decibels for low volume audio. You have been warned the easy isn't the best way
This shows that Avidemux has converted the AVI file to a FOURCC of DX50 required for Standalone DVD with DivX compatibility and a CBR 0x0055 MPEG-1,layer 3 the video bitstream was unpacked this will give you AVI v1.0 which you may have still problems with so leave is packed to ge the AVI v2.0 container
PROCEDURE THREE:
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If this does not work and you still get a progressive audio error when you convert it to a DVD you can use a combination of
AVIMux GUI ,
VirtualDubMod and
WinMP3 packer to split the Video and Audio change the audio stream to CBR and rejoin the two.
Open up the file in AVIMux GUI extract the binary of the audio track you need to right click it do get this then use WinMP3Packer to convert the extracted MP3 file into an MP3 file with a CBR of the same sample rate of 48KHz
Open up the full AVI in VirtualDubMod it will warn you about the improper VBR in the source click NO to rewriting the packet header, next change the video to Direct Stream Copy" and disable the audio track under the streams > stream list option and save as AVI the file with the audio VBR disabled
the audio stream must show hatched as below to ensure that the track is removed
Then I go back into VirtualDubMod, open up the AVI saved without audio, change the video to "Direct Stream Copy" go into Stream List add the re-encoded CBR MP3, and then save as AVI.
Check to see if the MP3 has been changed to CBR in GSpot also check it for sync errors fast forward to the middle and end and you will know straight away in VirtualDub or use another media player VLC is a good one that uses the free Libavcodecs.
You should then be able to convert the AVI to DVD format using
ConvertXtoDVD If you have burned the result to DVD, see if the result of the converted file (before it was burned to DVD) has the same synchronization problems in order to make sure that the audio problems are not due to bad media. You may have to redo the conversion with the option "Burn result to DVD" and/or "Delete folder after successful burn" unchecked Use the latest version of VLC
www.videolan.org to watch the result
However If the unburned result also has the problem, you can check "Don't check/fix audio discontinuities" (in settings under "Audio" tab) redo the conversion and see if the result is any better.
