[FFmpeg-devel,v12,3/8] avcodec/bsf: Add awebp2webp bitstream filter

From: Thilo Borgmann via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>

Splits a packet containing a webp animations into
one non-compliant packet per frame of the animation.
Skips RIFF and WEBP chunks for those packets except
for the first. Copyies ICC, EXIF and XMP chunks first
into each of the packets except for the first.
---
 configure                      |   1 +
 libavcodec/bitstream_filters.c |   1 +
 libavcodec/bsf/Makefile        |   1 +
 libavcodec/bsf/awebp2webp.c    | 350 +++++++++++++++++++++++++++++++++
 4 files changed, 353 insertions(+)
 create mode 100644 libavcodec/bsf/awebp2webp.c

On 17.04.24 21:19, Thilo Borgmann via ffmpeg-devel wrote:
> From: Thilo Borgmann via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
> 
> Splits a packet containing a webp animations into
> one non-compliant packet per frame of the animation.
> Skips RIFF and WEBP chunks for those packets except
> for the first. Copyies ICC, EXIF and XMP chunks first
> into each of the packets except for the first.
> ---
>   configure                      |   1 +
>   libavcodec/bitstream_filters.c |   1 +
>   libavcodec/bsf/Makefile        |   1 +
>   libavcodec/bsf/awebp2webp.c    | 350 +++++++++++++++++++++++++++++++++
>   4 files changed, 353 insertions(+)
>   create mode 100644 libavcodec/bsf/awebp2webp.c

build failed here. Updated patch attached.

Sorry,
Thilo
From 536dfc772ac273b0d3607545b8aea7a26ba84ac1 Mon Sep 17 00:00:00 2001
From: Thilo Borgmann via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
Date: Thu, 28 Mar 2024 15:08:53 +0100
Subject: [PATCH v12 3/8] avcodec/bsf: Add awebp2webp bitstream filter

Splits a packet containing a webp animations into
one non-compliant packet per frame of the animation.
Skips RIFF and WEBP chunks for those packets except
for the first. Copyies ICC, EXIF and XMP chunks first
into each of the packets except for the first.
---
 configure                      |   1 +
 libavcodec/bitstream_filters.c |   1 +
 libavcodec/bsf/Makefile        |   1 +
 libavcodec/bsf/awebp2webp.c    | 351 +++++++++++++++++++++++++++++++++
 4 files changed, 354 insertions(+)
 create mode 100644 libavcodec/bsf/awebp2webp.c

diff --git a/configure b/configure
index 55f1fc354d..2d08bc1fd8 100755
--- a/configure
+++ b/configure
@@ -3425,6 +3425,7 @@ aac_adtstoasc_bsf_select="adts_header mpeg4audio"
 av1_frame_merge_bsf_select="cbs_av1"
 av1_frame_split_bsf_select="cbs_av1"
 av1_metadata_bsf_select="cbs_av1"
+awebp2webp_bsf_select=""
 dts2pts_bsf_select="cbs_h264 h264parse"
 eac3_core_bsf_select="ac3_parser"
 evc_frame_merge_bsf_select="evcparse"
diff --git a/libavcodec/bitstream_filters.c b/libavcodec/bitstream_filters.c
index 12860c332b..af88283a8c 100644
--- a/libavcodec/bitstream_filters.c
+++ b/libavcodec/bitstream_filters.c
@@ -28,6 +28,7 @@ extern const FFBitStreamFilter ff_aac_adtstoasc_bsf;
 extern const FFBitStreamFilter ff_av1_frame_merge_bsf;
 extern const FFBitStreamFilter ff_av1_frame_split_bsf;
 extern const FFBitStreamFilter ff_av1_metadata_bsf;
+extern const FFBitStreamFilter ff_awebp2webp_bsf;
 extern const FFBitStreamFilter ff_chomp_bsf;
 extern const FFBitStreamFilter ff_dump_extradata_bsf;
 extern const FFBitStreamFilter ff_dca_core_bsf;
diff --git a/libavcodec/bsf/Makefile b/libavcodec/bsf/Makefile
index fb70ad0c21..48c67dd210 100644
--- a/libavcodec/bsf/Makefile
+++ b/libavcodec/bsf/Makefile
@@ -5,6 +5,7 @@ OBJS-$(CONFIG_AAC_ADTSTOASC_BSF)          += bsf/aac_adtstoasc.o
 OBJS-$(CONFIG_AV1_FRAME_MERGE_BSF)        += bsf/av1_frame_merge.o
 OBJS-$(CONFIG_AV1_FRAME_SPLIT_BSF)        += bsf/av1_frame_split.o
 OBJS-$(CONFIG_AV1_METADATA_BSF)           += bsf/av1_metadata.o
+OBJS-$(CONFIG_AWEBP2WEBP_BSF)             += bsf/awebp2webp.o
 OBJS-$(CONFIG_CHOMP_BSF)                  += bsf/chomp.o
 OBJS-$(CONFIG_DCA_CORE_BSF)               += bsf/dca_core.o
 OBJS-$(CONFIG_DTS2PTS_BSF)                += bsf/dts2pts.o
diff --git a/libavcodec/bsf/awebp2webp.c b/libavcodec/bsf/awebp2webp.c
new file mode 100644
index 0000000000..7edacee48f
--- /dev/null
+++ b/libavcodec/bsf/awebp2webp.c
@@ -0,0 +1,351 @@
+/*
+ * Animated WebP into non-compliant WebP bitstream filter
+ * Copyright (c) 2024 Thilo Borgmann <thilo.borgmann _at_ mail.de>
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * Animated WebP into non-compliant WebP bitstream filter
+ * Splits a packet containing a webp animations into
+ * one non-compliant packet per frame of the animation.
+ * Skips RIFF and WEBP chunks for those packets except
+ * for the first. Copyies ICC, EXIF and XMP chunks first
+ * into each of the packets except for the first.
+ * @author Thilo Borgmann <thilo.borgmann _at_ mail.de>
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "codec_id.h"
+#include "bytestream.h"
+#include "libavutil/error.h"
+#include "libavutil/mem.h"
+
+#include "bsf.h"
+#include "bsf_internal.h"
+#include "packet.h"
+
+#define VP8X_FLAG_ANIMATION             0x02
+#define VP8X_FLAG_XMP_METADATA          0x04
+#define VP8X_FLAG_EXIF_METADATA         0x08
+#define VP8X_FLAG_ALPHA                 0x10
+#define VP8X_FLAG_ICC                   0x20
+
+typedef struct WEBPBSFContext {
+    const AVClass *class;
+    GetByteContext gb;
+
+    AVPacket *last_pkt;
+    uint8_t *last_iccp;
+    uint8_t *last_exif;
+    uint8_t *last_xmp;
+
+    int iccp_size;
+    int exif_size;
+    int xmp_size;
+
+    int add_iccp;
+    int add_exif;
+    int add_xmp;
+
+    uint64_t last_pts;
+} WEBPBSFContext;
+
+static int save_chunk(WEBPBSFContext *ctx, uint8_t **buf, int *buf_size, uint32_t chunk_size)
+{
+    if (*buf || !buf_size || !chunk_size)
+        return 0;
+
+    *buf = av_malloc(chunk_size + 8);
+    if (!*buf)
+        return AVERROR(ENOMEM);
+
+    *buf_size = chunk_size + 8;
+
+    bytestream2_seek(&ctx->gb, -8, SEEK_CUR);
+    bytestream2_get_buffer(&ctx->gb, *buf, chunk_size + 8);
+
+    return 0;
+}
+
+static int awebp2webp_filter(AVBSFContext *ctx, AVPacket *out)
+{
+    WEBPBSFContext *s = ctx->priv_data;
+    AVPacket *in;
+    uint32_t chunk_type;
+    uint32_t chunk_size;
+    int64_t packet_start;
+    int64_t packet_end;
+    int64_t out_off;
+    int ret       = 0;
+    int is_frame  = 0;
+    int key_frame = 0;
+    int delay     = 0;
+    int out_size  = 0;
+    int has_anim  = 0;
+
+    // initialize for new packet
+    if (!bytestream2_size(&s->gb)) {
+        if (s->last_pkt)
+            av_packet_unref(s->last_pkt);
+
+        ret = ff_bsf_get_packet(ctx, &s->last_pkt);
+        if (ret < 0)
+            goto fail;
+
+        bytestream2_init(&s->gb, s->last_pkt->data, s->last_pkt->size);
+
+        av_freep(&s->last_iccp);
+        av_freep(&s->last_exif);
+        av_freep(&s->last_xmp);
+
+        // read packet scanning for metadata && animation
+        while (bytestream2_get_bytes_left(&s->gb) > 0) {
+            chunk_type = bytestream2_get_le32(&s->gb);
+            chunk_size = bytestream2_get_le32(&s->gb);
+
+            if (chunk_size == UINT32_MAX)
+                return AVERROR_INVALIDDATA;
+            chunk_size += chunk_size & 1;
+
+            if (!bytestream2_get_bytes_left(&s->gb) ||
+                 bytestream2_get_bytes_left(&s->gb) < chunk_size)
+                break;
+
+            if (chunk_type == MKTAG('R', 'I', 'F', 'F') && chunk_size > 4) {
+                chunk_size = 4;
+            }
+
+            switch (chunk_type) {
+            case MKTAG('I', 'C', 'C', 'P'):
+                if (!s->last_iccp) {
+                    ret = save_chunk(s, &s->last_iccp, &s->iccp_size, chunk_size);
+                    if (ret < 0)
+                        goto fail;
+                } else {
+                    bytestream2_skip(&s->gb, chunk_size);
+                }
+                break;
+
+            case MKTAG('E', 'X', 'I', 'F'):
+                if (!s->last_exif) {
+                    ret = save_chunk(s, &s->last_exif, &s->exif_size, chunk_size);
+                    if (ret < 0)
+                        goto fail;
+                } else {
+                    bytestream2_skip(&s->gb, chunk_size);
+                }
+                break;
+
+            case MKTAG('X', 'M', 'P', ' '):
+                if (!s->last_xmp) {
+                    ret = save_chunk(s, &s->last_xmp, &s->xmp_size, chunk_size);
+                    if (ret < 0)
+                        goto fail;
+                } else {
+                    bytestream2_skip(&s->gb, chunk_size);
+                }
+                break;
+
+            case MKTAG('A', 'N', 'M', 'F'):
+                has_anim = 1;
+                bytestream2_skip(&s->gb, chunk_size);
+                break;
+
+            default:
+                bytestream2_skip(&s->gb, chunk_size);
+                break;
+            }
+        }
+
+        // if no animation is found, pass-through the packet
+        if (!has_anim) {
+            av_packet_move_ref(out, s->last_pkt);
+            return 0;
+        }
+
+        // reset bytestream to beginning of packet
+        bytestream2_init(&s->gb, s->last_pkt->data, s->last_pkt->size);
+    }
+
+    // packet read completely, reset and ask for next packet
+    if (!bytestream2_get_bytes_left(&s->gb)) {
+        if (s->last_pkt)
+            av_packet_free(&s->last_pkt);
+        // reset to empty buffer for reinit with next real packet
+        bytestream2_init(&s->gb, NULL, 0);
+        return AVERROR(EAGAIN);
+    }
+
+    // start reading from packet until sub packet ready
+    packet_start = bytestream2_tell(&s->gb);
+    s->add_iccp  = 1;
+    s->add_exif  = 1;
+    s->add_xmp   = 1;
+
+    while (bytestream2_get_bytes_left(&s->gb) > 0) {
+        chunk_type = bytestream2_get_le32(&s->gb);
+        chunk_size = bytestream2_get_le32(&s->gb);
+
+        if (chunk_size == UINT32_MAX)
+            return AVERROR_INVALIDDATA;
+        chunk_size += chunk_size & 1;
+
+        if (!bytestream2_get_bytes_left(&s->gb) ||
+             bytestream2_get_bytes_left(&s->gb) < chunk_size)
+            break;
+
+        if (chunk_type == MKTAG('R', 'I', 'F', 'F') && chunk_size > 4) {
+            chunk_size = 4;
+            key_frame = 1;
+        }
+
+        switch (chunk_type) {
+        case MKTAG('I', 'C', 'C', 'P'):
+            s->add_iccp = 0;
+            bytestream2_skip(&s->gb, chunk_size);
+            break;
+
+        case MKTAG('E', 'X', 'I', 'F'):
+            s->add_exif = 0;
+            bytestream2_skip(&s->gb, chunk_size);
+            break;
+
+        case MKTAG('X', 'M', 'P', ' '):
+            s->add_xmp = 0;
+            bytestream2_skip(&s->gb, chunk_size);
+            break;
+
+        case MKTAG('V', 'P', '8', ' '):
+            if (is_frame) {
+                bytestream2_seek(&s->gb, -8, SEEK_CUR);
+                goto flush;
+            }
+            bytestream2_skip(&s->gb, chunk_size);
+            is_frame = 1;
+            break;
+
+        case MKTAG('V', 'P', '8', 'L'):
+            if (is_frame) {
+                bytestream2_seek(&s->gb, -8, SEEK_CUR);
+                goto flush;
+            }
+            bytestream2_skip(&s->gb, chunk_size);
+            is_frame = 1;
+            break;
+
+        case MKTAG('A', 'N', 'M', 'F'):
+            if (is_frame) {
+                bytestream2_seek(&s->gb, -8, SEEK_CUR);
+                goto flush;
+            }
+            bytestream2_skip(&s->gb, 12);
+            delay = bytestream2_get_le24(&s->gb);
+            bytestream2_skip(&s->gb, 1);
+            break;
+
+        default:
+            bytestream2_skip(&s->gb, chunk_size);
+            break;
+        }
+
+        packet_end = bytestream2_tell(&s->gb);
+    }
+
+flush:
+    // generate packet from data read so far
+    out_size = packet_end - packet_start;
+    out_off  = 0;
+
+    if (s->add_iccp && s->last_iccp)
+        out_size += s->iccp_size;
+    if (s->add_exif && s->last_exif)
+        out_size += s->exif_size;
+    if (s->add_xmp && s->last_xmp)
+        out_size += s->xmp_size;
+
+    ret = av_new_packet(out, out_size);
+    if (ret < 0)
+        goto fail;
+
+    // copy metadata
+    if (s->add_iccp && s->last_iccp) {
+        memcpy(out->data + out_off, s->last_iccp, s->iccp_size);
+        out_off += s->iccp_size;
+    }
+    if (s->add_exif && s->last_exif) {
+        memcpy(out->data + out_off, s->last_exif, s->exif_size);
+        out_off += s->exif_size;
+    }
+    if (s->add_xmp && s->last_xmp) {
+        memcpy(out->data + out_off, s->last_xmp, s->xmp_size);
+        out_off += s->xmp_size;
+    }
+
+    // copy frame data
+    memcpy(out->data + out_off, s->last_pkt->data + packet_start, packet_end - packet_start);
+
+    if (key_frame)
+        out->flags |= AV_PKT_FLAG_KEY;
+    else
+        out->flags &= ~AV_PKT_FLAG_KEY;
+
+    out->pts          = s->last_pts;
+    out->dts          = out->pts;
+    out->pos          = packet_start;
+    out->duration     = delay;
+    out->stream_index = s->last_pkt->stream_index;
+    out->time_base    = s->last_pkt->time_base;
+
+    s->last_pts += (delay > 0) ? delay : 1;
+
+    key_frame = 0;
+
+    return 0;
+
+fail:
+    if (ret < 0) {
+        av_packet_unref(out);
+        return ret;
+    }
+    av_packet_free(&in);
+
+    return ret;
+}
+
+static void awebp2webp_close(AVBSFContext *ctx)
+{
+    WEBPBSFContext *s = ctx->priv_data;
+    av_freep(&s->last_iccp);
+    av_freep(&s->last_exif);
+    av_freep(&s->last_xmp);
+}
+
+static const enum AVCodecID codec_ids[] = {
+    AV_CODEC_ID_WEBP, AV_CODEC_ID_NONE,
+};
+
+const FFBitStreamFilter ff_awebp2webp_bsf = {
+    .p.name         = "awebp2webp",
+    .p.codec_ids    = codec_ids,
+    .priv_data_size = sizeof(WEBPBSFContext),
+    .filter         = awebp2webp_filter,
+    .close          = awebp2webp_close,
+};