Why is my Audio frame rate showing differently to the Video frame rate

CubeAce wrote on 4/7/2019, 5:13 PM

Is this info from MediaInfo correct or is there something not being read or written correctly in the file?

It's not causing problems in MEP but I'm curious if anyone else has ever seen something similar.

I am using the most recent update of MediaInfo.

General
Complete name                            : V:\2019\Dockyard Film location project\Cavalier\DJI_0571.MP4
Format                                   : MPEG-4
Format profile                           : JVT
Codec ID                                 : avc1 (avc1/isom)
File size                                : 955 MiB
Duration                                 : 3 min 47 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 35.2 Mb/s
Encoded date                             : UTC 2019-04-03 10:50:59
Tagged date                              : UTC 2019-04-03 10:50:59
Comment                                  : DE=None, Type=Normal, HQ=Normal, Mode=P
gpt                                      : -0.20
gyw                                      : +1.40
grl                                      : +0.00

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4
Format settings                          : CABAC / 1 Ref Frames
Format settings, CABAC                   : Yes
Format settings, RefFrames               : 1 frame
Format settings, GOP                     : M=1, N=30
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 3 min 47 s
Bit rate mode                            : Variable
Bit rate                                 : 35.0 Mb/s
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (30000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.563
Stream size                              : 950 MiB (99%)
Title                                    : DJI.AVC
Language                                 : English
Encoded date                             : UTC 2019-04-03 10:50:59
Tagged date                              : UTC 2019-04-03 10:50:59
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 3 min 47 s
Bit rate mode                            : Constant
Bit rate                                 : 192 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 5.14 MiB (1%)
Title                                    : DJI.AAC
Language                                 : English
Encoded date                             : UTC 2019-04-03 10:50:59
Tagged date                              : UTC 2019-04-03 10:50:59

Other
Type                                     : meta
Duration                                 : 1 s 0 ms
Default                                  : No
Bit rate mode                            : CBR

No other video files from other sources I have do this. The frame rate isn't even mentioned for audio in other video files I get from other cameras. Everything stays in sync, even when mixing files from different cameras, but could it start a problem?

I ask because I have a large project coming up that I won't be able to re-take.

Comments

emmrecs wrote on 4/8/2019, 3:46 AM

@CubeAce

Yes, I've seen the same thing happen on various MediaInfo reports, always without problem, i.e. no "damage" occurs to the file when editing/exporting etc.

My guess is that the "frames" are not actually the same thing, i.e. a video "frame" is different to an audio "frame"!

Jeff

CubeAce wrote on 4/8/2019, 4:10 AM

@emmrecs

Hi Jeff.

Thank you for your reply, at least I know it's not a one-off problem with my equipment. I have noticed as well with these particular video files that no matter the frame rate of the video, the audio frame rate stays the same. Maybe it's the codec wrapper that causes this but as long as there are no side effects for editing I won't bother worrying over it.