Flash .flv video out of sync (original video is perfect with double audio s

[TACtech]

I use portable audio recorder and I sync the audio in post. I edit my videos in Vegas and my timeline is set correctly. No matter what template I pick or format I render to (.avi .m2t .mp4 etc.) the video comes out fine. Every time, I try to convert the same video to .flv using AVS Video Converter 8.1 (Audio Codec MPEG-2/4 or MP3 with Sample Rate: 44100Hz and Bit Rate from 192 or 320 Size: 16bit) I get video and audio out of sync. I even tried adding a white noise and going that route without much success. Anyone experienced have a solution for this?

Thank you in advance!

[Baldrick]

MP4 works fine in flash so you can you can export to that in vegas. It must be mp4 with h264 video and aac audio.

But if you want it in a flv container then try convert with something else like freemake video converter or xmedia recode.

[TACtech]

Baldrick Thank you very much!

I just ran few short tests on converting mp4 into a .flv container with both apps you had suggested to me and Voila! It works!
I just do not understand why other application make the video and audio out of sync. The only free app the had worked for me before these two was SUPER but with very limited way of controlling the flash video's bit rate.

I also noticed that there is a audio delay relative to video in a converted flash video (it plays as it supposed to, meaning everything is in sync).

Audio
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 10
Duration                                 : 3mn 15s
Bit rate                                 : 313 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Delay relative to video                  : 70ms
Stream size                              : 7.27 MiB (3%)

The original mp4 video file doesn't show this DELAY:

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 36s 943ms
Bit rate mode                            : Constant
Bit rate                                 : 320 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 1.41 MiB (3%)
Language                                 : English
Encoded date                             : UTC 2012-04-03 05:58:18
Tagged date                              : UTC 2012-04-03 05:58:18

Is this something Vegas fixes on a fly and I do not get to see it? What would be a proper way of syncing double system audio?


I appreciate any info and direction.

Cheers!