lavc: Add h264_redundant_pps bitstream filter

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.

A new single global PPS is created, and all of the redundant PPSs
within the stream are removed.

(cherry picked from commit e6874bc3af2f09af39b5d91b9c5f9ded67459696)

1 files changed, 178 insertions, 0 deletions

diff --git a/libavcodec/h264_redundant_pps_bsf.c b/libavcodec/h264_redundant_pps_bsf.c
new file mode 100644
index 0000000..26baca8
--- /dev/null
+++ b/libavcodec/h264_redundant_pps_bsf.c
@@ -0,0 +1,178 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <string.h>
+
+#include "libavutil/common.h"
+#include "libavutil/mem.h"
+
+#include "bsf.h"
+#include "cbs.h"
+#include "cbs_h264.h"
+#include "h264.h"
+
+
+typedef struct H264RedundantPPSContext {
+    CodedBitstreamContext *input;
+    CodedBitstreamContext *output;
+
+    CodedBitstreamFragment access_unit;
+
+    int global_pic_init_qp;
+    int current_pic_init_qp;
+} H264RedundantPPSContext;
+
+
+static int h264_redundant_pps_fixup_pps(H264RedundantPPSContext *ctx,
+                                        H264RawPPS *pps)
+{
+    // 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;
+    pps->pic_init_qp_minus26 = ctx->global_pic_init_qp - 26;
+
+    // Some PPSs have this set, so it must be set in all of them.
+    // (Slices which do not use such a PPS on input will still have
+    // *_weight_l*flag as zero and therefore write equivalently.)
+    pps->weighted_pred_flag = 1;
+
+    return 0;
+}
+
+static int h264_redundant_pps_fixup_slice(H264RedundantPPSContext *ctx,
+                                          H264RawSliceHeader *slice)
+{
+    int qp;
+
+    qp = ctx->current_pic_init_qp + slice->slice_qp_delta;
+    slice->slice_qp_delta = qp - ctx->global_pic_init_qp;
+
+    return 0;
+}
+
+static int h264_redundant_pps_filter(AVBSFContext *bsf, AVPacket *out)
+{
+    H264RedundantPPSContext *ctx = bsf->priv_data;
+    AVPacket *in;
+    CodedBitstreamFragment *au = &ctx->access_unit;
+    int au_has_sps;
+    int err, i;
+
+    err = ff_bsf_get_packet(bsf, &in);
+    if (err < 0)
+        return err;
+
+    err = ff_cbs_read_packet(ctx->input, au, in);
+    if (err < 0)
+        return err;
+
+    au_has_sps = 0;
+    for (i = 0; i < au->nb_units; i++) {
+        CodedBitstreamUnit *nal = &au->units[i];
+
+        if (nal->type == H264_NAL_SPS)
+            au_has_sps = 1;
+        if (nal->type == H264_NAL_PPS) {
+            h264_redundant_pps_fixup_pps(ctx, nal->content);
+            if (!au_has_sps) {
+                av_log(ctx, AV_LOG_VERBOSE, "Deleting redundant PPS "
+                       "at %"PRId64".\n", in->pts);
+                ff_cbs_delete_unit(ctx->input, au, i);
+            }
+        }
+        if (nal->type == H264_NAL_SLICE ||
+            nal->type == H264_NAL_IDR_SLICE) {
+            H264RawSlice *slice = nal->content;
+            h264_redundant_pps_fixup_slice(ctx, &slice->header);
+        }
+    }
+
+    err = ff_cbs_write_packet(ctx->output, out, au);
+    if (err < 0)
+        return err;
+
+    ff_cbs_fragment_uninit(ctx->output, au);
+
+    err = av_packet_copy_props(out, in);
+    if (err < 0)
+        return err;
+
+    av_packet_free(&in);
+
+    return 0;
+}
+
+static int h264_redundant_pps_init(AVBSFContext *bsf)
+{
+    H264RedundantPPSContext *ctx = bsf->priv_data;
+    CodedBitstreamFragment *au = &ctx->access_unit;
+    int err, i;
+
+    err = ff_cbs_init(&ctx->input, AV_CODEC_ID_H264, bsf);
+    if (err < 0)
+        return err;
+
+    err = ff_cbs_init(&ctx->output, AV_CODEC_ID_H264, bsf);
+    if (err < 0)
+        return err;
+
+    ctx->global_pic_init_qp = 26;
+
+    if (bsf->par_in->extradata) {
+        err = ff_cbs_read_extradata(ctx->input, au, bsf->par_in);
+        if (err < 0) {
+            av_log(bsf, AV_LOG_ERROR, "Failed to read extradata.\n");
+            return err;
+        }
+
+        for (i = 0; i < au->nb_units; i++) {
+            if (au->units[i].type == H264_NAL_PPS)
+                h264_redundant_pps_fixup_pps(ctx, au->units[i].content);
+        }
+
+        err = ff_cbs_write_extradata(ctx->output, bsf->par_out, au);
+        if (err < 0) {
+            av_log(bsf, AV_LOG_ERROR, "Failed to write extradata.\n");
+            return err;
+        }
+
+        ff_cbs_fragment_uninit(ctx->output, au);
+    }
+
+    return 0;
+}
+
+static void h264_redundant_pps_close(AVBSFContext *bsf)
+{
+    H264RedundantPPSContext *ctx = bsf->priv_data;
+    ff_cbs_close(&ctx->input);
+    ff_cbs_close(&ctx->output);
+}
+
+static const enum AVCodecID h264_redundant_pps_codec_ids[] = {
+    AV_CODEC_ID_H264, AV_CODEC_ID_NONE,
+};
+
+const AVBitStreamFilter ff_h264_redundant_pps_bsf = {
+    .name           = "h264_redundant_pps",
+    .priv_data_size = sizeof(H264RedundantPPSContext),
+    .init           = &h264_redundant_pps_init,
+    .close          = &h264_redundant_pps_close,
+    .filter         = &h264_redundant_pps_filter,
+    .codec_ids      = h264_redundant_pps_codec_ids,
+};