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>

1 files changed, 155 insertions, 0 deletions

diff --git a/libavcodec/av1_frame_merge_bsf.c b/libavcodec/av1_frame_merge_bsf.c
new file mode 100644
index 0000000000..49397111fc
--- /dev/null
+++ b/libavcodec/av1_frame_merge_bsf.c
@@ -0,0 +1,155 @@
+/*
+ * 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,
+};