avcodec: add an AV1 frame merge bitstream filter

This BSF takes Temporal Units split across different AVPackets and merges them
by looking for Temporal Delimiter OBUs.
Signed-off-by: James Almer <jamrial@gmail.com>

Changelog

@@ -22,6 +22,7 @@ version <next>:
 - median filter
 - QSV-accelerated VP9 encoding
 - AV1 encoding support via librav1e
+- AV1 frame merge bitstream filter
 
 
 version 4.2:

configure

@@ -3115,6 +3115,7 @@ vc1_parser_select="vc1dsp"
 
 # bitstream_filters
 aac_adtstoasc_bsf_select="adts_header"
+av1_frame_merge_bsf_select="cbs_av1"
 av1_frame_split_bsf_select="cbs_av1"
 av1_metadata_bsf_select="cbs_av1"
 eac3_core_bsf_select="ac3_parser"

libavcodec/Makefile

@@ -1075,6 +1075,7 @@ OBJS-$(CONFIG_XMA_PARSER)              += xma_parser.o
 # bitstream filters
 OBJS-$(CONFIG_AAC_ADTSTOASC_BSF)          += aac_adtstoasc_bsf.o mpeg4audio.o
 OBJS-$(CONFIG_AV1_METADATA_BSF)           += av1_metadata_bsf.o
+OBJS-$(CONFIG_AV1_FRAME_MERGE_BSF)        += av1_frame_merge_bsf.o
 OBJS-$(CONFIG_AV1_FRAME_SPLIT_BSF)        += av1_frame_split_bsf.o
 OBJS-$(CONFIG_CHOMP_BSF)                  += chomp_bsf.o
 OBJS-$(CONFIG_DUMP_EXTRADATA_BSF)         += dump_extradata_bsf.o

libavcodec/av1_frame_merge_bsf.c

+/*
+ * Copyright (c) 2019 James Almer <jamrial@gmail.com>
+ *
+ * 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 "avcodec.h"
+#include "bsf.h"
+#include "cbs.h"
+#include "cbs_av1.h"
+
+typedef struct AV1FMergeContext {
+    CodedBitstreamContext *cbc;
+    CodedBitstreamFragment frag[2];
+    AVPacket *pkt, *in;
+    int idx;
+} AV1FMergeContext;
+
+static void av1_frame_merge_flush(AVBSFContext *bsf)
+{
+    AV1FMergeContext *ctx = bsf->priv_data;
+
+    ff_cbs_fragment_reset(ctx->cbc, &ctx->frag[0]);
+    ff_cbs_fragment_reset(ctx->cbc, &ctx->frag[1]);
+    av_packet_unref(ctx->in);
+    av_packet_unref(ctx->pkt);
+}
+
+static int av1_frame_merge_filter(AVBSFContext *bsf, AVPacket *out)
+{
+    AV1FMergeContext *ctx = bsf->priv_data;
+    CodedBitstreamFragment *frag = &ctx->frag[ctx->idx], *tu = &ctx->frag[!ctx->idx];
+    AVPacket *in = ctx->in, *buffer_pkt = ctx->pkt;
+    int err, i;
+
+    err = ff_bsf_get_packet_ref(bsf, in);
+    if (err < 0) {
+        if (err == AVERROR_EOF && tu->nb_units > 0)
+            goto eof;
+        return err;
+    }
+
+    err = ff_cbs_read_packet(ctx->cbc, frag, in);
+    if (err < 0) {
+        av_log(bsf, AV_LOG_ERROR, "Failed to read packet.\n");
+        goto fail;
+    }
+
+    if (frag->nb_units == 0) {
+        av_log(bsf, AV_LOG_ERROR, "No OBU in packet.\n");
+        err = AVERROR_INVALIDDATA;
+        goto fail;
+    }
+
+    if (tu->nb_units == 0 && frag->units[0].type != AV1_OBU_TEMPORAL_DELIMITER) {
+        av_log(bsf, AV_LOG_ERROR, "Missing Temporal Delimiter.\n");
+        err = AVERROR_INVALIDDATA;
+        goto fail;
+    }
+
+    for (i = 1; i < frag->nb_units; i++) {
+        if (frag->units[i].type == AV1_OBU_TEMPORAL_DELIMITER) {
+            av_log(bsf, AV_LOG_ERROR, "Temporal Delimiter in the middle of a packet.\n");
+            err = AVERROR_INVALIDDATA;
+            goto fail;
+        }
+    }
+
+    if (tu->nb_units > 0 && frag->units[0].type == AV1_OBU_TEMPORAL_DELIMITER) {
+eof:
+        err = ff_cbs_write_packet(ctx->cbc, buffer_pkt, tu);
+        if (err < 0) {
+            av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
+            goto fail;
+        }
+        av_packet_move_ref(out, buffer_pkt);
+
+        // Swap fragment index, to avoid copying fragment references.
+        ctx->idx = !ctx->idx;
+    } else {
+        for (i = 0; i < frag->nb_units; i++) {
+            err = ff_cbs_insert_unit_content(ctx->cbc, tu, -1, frag->units[i].type,
+                                             frag->units[i].content, frag->units[i].content_ref);
+            if (err < 0)
+                goto fail;
+        }
+
+        err = AVERROR(EAGAIN);
+    }
+
+    // Buffer packets with timestamps. There should be at most one per TU, be it split or not.
+    if (!buffer_pkt->data && in->pts != AV_NOPTS_VALUE)
+        av_packet_move_ref(buffer_pkt, in);
+    else
+        av_packet_unref(in);
+
+    ff_cbs_fragment_reset(ctx->cbc, &ctx->frag[ctx->idx]);
+
+fail:
+    if (err < 0 && err != AVERROR(EAGAIN))
+        av1_frame_merge_flush(bsf);
+
+    return err;
+}
+
+static int av1_frame_merge_init(AVBSFContext *bsf)
+{
+    AV1FMergeContext *ctx = bsf->priv_data;
+
+    ctx->in  = av_packet_alloc();
+    ctx->pkt = av_packet_alloc();
+    if (!ctx->in || !ctx->pkt)
+        return AVERROR(ENOMEM);
+
+    return ff_cbs_init(&ctx->cbc, AV_CODEC_ID_AV1, bsf);
+}
+
+static void av1_frame_merge_close(AVBSFContext *bsf)
+{
+    AV1FMergeContext *ctx = bsf->priv_data;
+
+    ff_cbs_fragment_free(ctx->cbc, &ctx->frag[0]);
+    ff_cbs_fragment_free(ctx->cbc, &ctx->frag[1]);
+    av_packet_free(&ctx->in);
+    av_packet_free(&ctx->pkt);
+    ff_cbs_close(&ctx->cbc);
+}
+
+static const enum AVCodecID av1_frame_merge_codec_ids[] = {
+    AV_CODEC_ID_AV1, AV_CODEC_ID_NONE,
+};
+
+const AVBitStreamFilter ff_av1_frame_merge_bsf = {
+    .name           = "av1_frame_merge",
+    .priv_data_size = sizeof(AV1FMergeContext),
+    .init           = av1_frame_merge_init,
+    .flush          = av1_frame_merge_flush,
+    .close          = av1_frame_merge_close,
+    .filter         = av1_frame_merge_filter,
+    .codec_ids      = av1_frame_merge_codec_ids,
+};

libavcodec/bitstream_filters.c

@@ -25,6 +25,7 @@
 #include "bsf.h"
 
 extern const AVBitStreamFilter ff_aac_adtstoasc_bsf;
+extern const AVBitStreamFilter ff_av1_frame_merge_bsf;
 extern const AVBitStreamFilter ff_av1_frame_split_bsf;
 extern const AVBitStreamFilter ff_av1_metadata_bsf;
 extern const AVBitStreamFilter ff_chomp_bsf;

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  58
-#define LIBAVCODEC_VERSION_MINOR  61
+#define LIBAVCODEC_VERSION_MINOR  62
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \