TimeSpan overflow in QuickTimeMetadataReader (with bad MP4 file)

[kirk-marple]

Ran across this recently, and just wanted to post this for awareness.

In ReadMetadata, if the timeScale comes back as zero (because of bad header data), this can cause a divide by zero error, and overflow creating the TimeSpan.FromSeconds.

I have a file from 2017, taken on a Samsung Android phone. I'm guessing they had a bug in their MP4 writer back then.

The created and modified dates that are parsed are bogus (like 1908 for created date).

Line 249: directory.Set(QuickTimeMovieHeaderDirectory.TagCreated, _epoch.AddTicks(TimeSpan.TicksPerSecond a.Reader.GetUInt32())); directory.Set(QuickTimeMovieHeaderDirectory.TagModified, _epoch.AddTicks(TimeSpan.TicksPerSecond a.Reader.GetUInt32())); var timeScale = a.Reader.GetUInt32(); directory.Set(QuickTimeMovieHeaderDirectory.TagTimeScale, timeScale); directory.Set(QuickTimeMovieHeaderDirectory.TagDuration, TimeSpan.FromSeconds(a.Reader.GetUInt32() / (double)timeScale));

Here's the MediaInfo output from it:

General Complete name : C:\Users\kirk\Pictures\Austin\20161126_132809.mp4 Format : MPEG-4 Format profile : Base Media / Version 2 Codec ID : mp42 (isom/mp42) File size : 9.13 MiB Duration : 9 s 380 ms Overall bit rate mode : Variable Overall bit rate : 8 166 kb/s Tagged date : UTC 2016-11-27 01:07:53 xyz : +30.2627-097.9380/

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, Reference frames : 1 frame Format settings, GOP : M=1, N=60 Codec ID : avc1 Codec ID/Info : Advanced Video Coding Duration : 9 s 333 ms Bit rate : 8 010 kb/s Maximum bit rate : 9 410 kb/s Width : 1 080 pixels Height : 1 920 pixels Display aspect ratio : 0.563 Frame rate mode : Constant Frame rate : 30.000 FPS Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Bits/(Pixel*Frame) : 0.129 Stream size : 8.91 MiB (98%) Tagged date : UTC 2016-11-27 01:07:54 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 : 9 s 380 ms Bit rate mode : Variable Bit rate : 192 kb/s Maximum bit rate : 203 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 44.1 kHz Frame rate : 43.066 FPS (1024 SPF) Compression mode : Lossy Stream size : 220 KiB (2%) Title : IsoMedia File Produced by Google, 5-11-2011 Language : English Encoded date : UTC 2016-11-27 01:07:53 Tagged date : UTC 2016-11-27 01:07:54

[drewnoakes]

Hey Kirk. Are you able to provide that sample file?

[drewnoakes]

I believe that PR fixes it, but cannot verify that the resulting duration value makes any sense. It'd be great to have a test file.

[kirk-marple]

@drewnoakes Here you go. Enjoy the tortoises :)

20161126_132809.zip

[drewnoakes]

270 fixed the exception, but the resulting value is garbage:

[QuickTime Movie Header - 0x0006] Duration = 41239.01:07:53

Java produces more sensible values here. We should compare the behaviour of both to understand the difference.