From 6d5a0998b69a8ec7e67f880d3ff81367bc439574 Mon Sep 17 00:00:00 2001 From: Marth64 Date: Sat, 12 Oct 2024 11:44:49 -0500 Subject: [PATCH] doc/bitstream_filters: elaborate on h264_redundant_pps Signed-off-by: Marth64 --- doc/bitstream_filters.texi | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi index e1cb87a522..1e625ac913 100644 --- a/doc/bitstream_filters.texi +++ b/doc/bitstream_filters.texi @@ -423,9 +423,21 @@ Please note that this filter is auto-inserted for MPEG-TS (muxer @section h264_redundant_pps -This applies a specific fixup to some Blu-ray streams which contain -redundant PPSs modifying irrelevant parameters of the stream which -confuse other transformations which require correct extradata. +This applies a specific fixup to some Blu-ray BDMV H264 streams +which contain redundant PPSs. The PPSs modify irrelevant parameters +of the stream, confusing other transformations which require +the correct extradata. + +The encoder used on these impacted streams adds extra PPSs throughout +the stream, varying the initial QP and whether weighted prediction +was enabled. This causes issues after copying the stream into +a global header container, as the starting PPS is not suitable +for the rest of the stream. One side effect, for example, +is seeking will return garbled output until a new PPS appears. + +This BSF removes the extra PPSs and rewrites the slice headers +such that the stream uses a single leading PPS in the global header, +which resolves the issue. @section hevc_metadata