VTDecompressionSession on iOS cannot decode interlaced H264 video

Number:rdar://30669495 Date Originated:
Status:Open Resolved:
Product: Product Version:
Classification: Reproducible:
Core Media

On iOS devices, VTDecompressionSession cannot handle interlaced H264 video input. The same input file works fine on macOS with VT. And VT on iOS works fine with progressive H264, as well as H264 with MBAFF interlacing.

Here is an example of a mp4 file which cannot be decoded on iOS with VT: https://s3.amazonaws.com/tmm1/videotoolbox/interlaced2.mp4

Steps to Reproduce:
1. Create VTDecompressionSession
2. Feed interlaced H264 video to session via VTDecompressionSessionDecodeFrame

Expected Results:
Expect VTDecompressionSessionDecodeFrame() to succeed

Actual Results:
VTDecompressionSessionDecodeFrame returns -12911 malfunction error

iOS 10

iPhone 6S


Apple Developer Relations

Engineering has provided the following feedback regarding this issue:

Correct and intentional. Please stop using interlaced video.

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