[FFmpeg-devel,v2,08/11] h264_redundant_pps: Make it reference-compatible

Submitted by Mark Thompson on May 20, 2019, 11:02 p.m.

Details

Message ID 20190520230224.19221-8-sw@jkqxz.net
State New
Headers show

Commit Message

Mark Thompson May 20, 2019, 11:02 p.m.
From: Andreas Rheinhardt <andreas.rheinhardt@googlemail.com>

Since c6a63e11092c975b89d824f08682fe31948d3686, the parameter sets
modified as content of PPS units were references shared with the
CodedBitstreamH264Context, so modifying them alters the parsing process
of future access units which meant that frames often got discarded
because invalid values were parsed. This patch makes h264_redundant_pps
compatible with the reality of reference-counted parameter sets.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@googlemail.com>
---
 libavcodec/h264_redundant_pps_bsf.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

Patch hide | download patch | download mbox

diff --git a/libavcodec/h264_redundant_pps_bsf.c b/libavcodec/h264_redundant_pps_bsf.c
index db8717d69a..b98c344058 100644
--- a/libavcodec/h264_redundant_pps_bsf.c
+++ b/libavcodec/h264_redundant_pps_bsf.c
@@ -40,8 +40,19 @@  typedef struct H264RedundantPPSContext {
 
 
 static int h264_redundant_pps_fixup_pps(H264RedundantPPSContext *ctx,
-                                        H264RawPPS *pps)
+                                        CodedBitstreamUnit *unit)
 {
+    H264RawPPS *pps;
+    int err;
+
+    // The changes we are about to perform affect the parsing process,
+    // so we must make sure that the PPS is writable, otherwise the
+    // parsing of future slices will be incorrect and even raise errors.
+    err = ff_cbs_make_unit_writable(ctx->input, unit);
+    if (err < 0)
+        return err;
+    pps = unit->content;
+
     // Record the current value of pic_init_qp in order to fix up
     // following slices, then overwrite with the global value.
     ctx->current_pic_init_qp = pps->pic_init_qp_minus26 + 26;
@@ -89,7 +100,7 @@  static int h264_redundant_pps_filter(AVBSFContext *bsf, AVPacket *out)
         if (nal->type == H264_NAL_SPS)
             au_has_sps = 1;
         if (nal->type == H264_NAL_PPS) {
-            err = h264_redundant_pps_fixup_pps(ctx, nal->content);
+            err = h264_redundant_pps_fixup_pps(ctx, nal);
             if (err < 0)
                 goto fail;
             if (!au_has_sps) {
@@ -151,7 +162,7 @@  static int h264_redundant_pps_init(AVBSFContext *bsf)
 
         for (i = 0; i < au->nb_units; i++) {
             if (au->units[i].type == H264_NAL_PPS) {
-                err = h264_redundant_pps_fixup_pps(ctx, au->units[i].content);
+                err = h264_redundant_pps_fixup_pps(ctx, &au->units[i]);
                 if (err < 0)
                     goto fail;
             }