obs-ffmpeg: Fix B-frame offset calculation in AMF - #13762
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| amf_int64 b_max = 0; | ||
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| if (get_av1_property(enc, B_PIC_PATTERN, &b_frames) && | ||
| get_av1_property(enc, MAX_CONSECUTIVE_BPICTURES, &b_max)) { |
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For AV1 this code shouldn't exist at all because it doesn't use frame-reordering. See also a similar change for NVIDIA here: #10996
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AVC and AV1 encoders in AMF that support B-frames were incrementing dts_offset even when B-frames were set to 0. For AVC, adjust the dts_offset only when B-frames are supported and are greater than 0, and clamp to maximum supported. For AV1, remove the dts_offset code completely because it is being ignored anyway. AV1 handles B-frames and offsets differently; refer to [1] for details. [1]: obsproject#10996
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AMF AVC and AV1 encoders support B-frames in more recent GPUs, however the
enc->dts_offsetwas being incremented even when b-frames were set to 0.For AVC, this caused IVS Stages to reject the stream because the offset is used to infer the presence of B-frames, which are not supported by IVS Stages (and WebRTC).
For AV1, the code is not needed and was removed. See below for details.
Description
For AVC, only increment the
enc->dts_offsetif the AMF encoder supports B-frames and b-frames are greater than 0.For AV1, remove the
dts_offsetcalculation fromamf_av1_create_internal. This code was dead —convert_to_encoder_packetalready excludes AV1 from the DTS subtraction (added inb2d83efcf, PR #10996), since AV1 handles frame reordering transparently and doesn't require decode-order delay compensation at the mux layer.The AV1
dts_offsetblock was introduced in1a2f8c284(AMD AV1 B-frame support) as a mechanical copy of the AVC pattern without accounting for this exclusion. This aligns with the NVENC implementation (plugins/obs-nvenc/nvenc.c), which similarly guards its DTS adjustment withif (enc->codec != CODEC_AV1)and has no offset calculation in its AV1 path.Motivation and Context
The original bug report at #13723 provides the details.
How Has This Been Tested?
I created an IVS Stage and reproduced the problem initially, then implemented the fix and tested on the same stage. There were no disconnects after the fix was in place.
Types of changes
Checklist: