WebEx MP4 audio distorted in Vegas Pro 15, high-pitched as if sped-up

kerumbo wrote on 10/17/2018, 9:43 AM

I imported an MP4 file from WebEx into Vegas Pro 15, and find that the audio is distorted, with a high-pitched, speeded-up "chipmunk" sound. Unfortunately WebEx exports MP4s with some unusually low specs -- for example, the video is 5 FPS. They play OK outside of Vegas (or in several video editors other than Vegas). Is there a workaround in Vegas to let me work with these files? By the way, Vegas can use WebEx's WMV files (by automatically offering to build an audio proxy file when I import), but who wants to use WMV. Here is the info on the MP4 file that has the audio issue in Vegas Pro 15 -- any tips will be appreciated!

General
Complete name                            : H:\Live Review of ProQuest Support Center Changes -20181016 1701-1.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (mp42/isom)
File size                                : 9.25 MiB
Duration                                 : 49 min 4 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 26.3 kb/s
Encoded date                             : UTC 2018-10-16 20:43:43
Tagged date                              : UTC 2018-10-16 21:32:55
Writing application                      : FAAC 1.28

Video
ID                                       : 2
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L4
Format settings                          : 9 Ref Frames
Format settings, CABAC                   : No
Format settings, RefFrames               : 9 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 49 min 4 s
Bit rate                                 : 11.2 kb/s
Width                                    : 1 024 pixels
Height                                   : 768 pixels
Display aspect ratio                     : 4:3
Frame rate mode                          : Constant
Frame rate                               : 5.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.003
Stream size                              : 3.92 MiB (42%)
Language                                 : English
Encoded date                             : UTC 2018-10-16 21:32:55
Tagged date                              : UTC 2018-10-16 21:32:55

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : mp4a-40-2
Duration                                 : 49 min 4 s
Bit rate mode                            : Variable
Bit rate                                 : 14.7 kb/s
Maximum bit rate                         : 19.6 kb/s
Channel(s)                               : 2 channels
Channel(s)_Original                      : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 8 000 Hz
Frame rate                               : 7.813 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 5.16 MiB (56%)
Language                                 : English
Encoded date                             : UTC 2018-10-16 20:43:43
Tagged date                              : UTC 2018-10-16 21:32:55

 

 

Comments

ryclark wrote on 10/17/2018, 11:42 AM

Apart from the low video frame rate the audio appears to be recorded with only 8kHz sample rate rather than the standard 48kHz. Hence the speeded up screechy nature of the sound. You will need to sample rate convert it to 48kHz to sound anything like normal. However the audio quality will sound pretty dire recorded at that sample rate and bit depth.

NickHope wrote on 10/17/2018, 10:25 PM

See this, especially point #6: https://www.vegascreativesoftware.info/us/forum/faq-why-won-t-vegas-open-my-file-correctly-codecs-converters-etc--104572/

kerumbo wrote on 10/18/2018, 7:13 AM

Thanks for the replies. I agree that 8-bit audio is a likely issue (WebEx does some extreme things to reduce file-size). Nick, your link is great, and that page is a keeper -- thanks. I tried the steps re: #6, to disable the SO4, but this resulted in Vegas 15 not being able to see the audio stream at all. Fortunately I don't need to edit these WebEx files too often or apply a lot of effects to them, so I'll probably just use another product for them. But I learned a lot from the link.