avformat/jpegxl_anim_dec: add animated JPEG XL demuxer

Animated JPEG XL files requires a separate demuxer than image2, because
the timebase information is set by the demuxer. Should the timebase of
an animated JPEG XL file be incompatible with the timebase set by the
image2pipe demuxer (usually 1/25 unless set otherwise), rescaling will
fail. Adding a separate demuxer for animated JPEG XL files allows the
timebase to be set correctly.

Signed-off-by: Leo Izen <leo.izen@gmail.com>

MAINTAINERS

@@ -432,6 +432,7 @@ Muxers/Demuxers:
   ipmovie.c                             Mike Melanson
   ircam*                                Paul B Mahol
   iss.c                                 Stefan Gehrer
+  jpegxl_anim_dec.c                     Leo Izen
   jpegxl_probe.*                        Leo Izen
   jvdec.c                               Peter Ross
   kvag.c                                Zane van Iperen

libavformat/Makefile

@@ -316,6 +316,7 @@ OBJS-$(CONFIG_IVF_MUXER)                 += ivfenc.o
 OBJS-$(CONFIG_IVR_DEMUXER)               += rmdec.o rm.o rmsipr.o
 OBJS-$(CONFIG_JACOSUB_DEMUXER)           += jacosubdec.o subtitles.o
 OBJS-$(CONFIG_JACOSUB_MUXER)             += jacosubenc.o rawenc.o
+OBJS-$(CONFIG_JPEGXL_ANIM_DEMUXER)       += jpegxl_anim_dec.o jpegxl_probe.o
 OBJS-$(CONFIG_JV_DEMUXER)                += jvdec.o
 OBJS-$(CONFIG_KUX_DEMUXER)               += flvdec.o
 OBJS-$(CONFIG_KVAG_DEMUXER)              += kvag.o

libavformat/allformats.c

@@ -238,6 +238,7 @@ extern const AVInputFormat  ff_ivr_demuxer;
 extern const AVInputFormat  ff_jacosub_demuxer;
 extern const FFOutputFormat ff_jacosub_muxer;
 extern const AVInputFormat  ff_jv_demuxer;
+extern const AVInputFormat  ff_jpegxl_anim_demuxer;
 extern const AVInputFormat  ff_kux_demuxer;
 extern const AVInputFormat  ff_kvag_demuxer;
 extern const FFOutputFormat ff_kvag_muxer;

libavformat/img2dec.c

@@ -850,7 +850,7 @@ static int jpegxl_probe(const AVProbeData *p)
     if (AV_RL16(b) != FF_JPEGXL_CODESTREAM_SIGNATURE_LE)
         return 0;
 #if CONFIG_IMAGE_JPEGXL_PIPE_DEMUXER
-    if (ff_jpegxl_verify_codestream_header(p->buf, p->buf_size) >= 0)
+    if (ff_jpegxl_verify_codestream_header(p->buf, p->buf_size, 1) >= 0)
         return AVPROBE_SCORE_MAX - 2;
 #endif
     return 0;

libavformat/jpegxl_anim_dec.c

@@ -0,0 +1,266 @@
+/*
+ * Animated JPEG XL Demuxer
+ * Copyright (c) 2023 Leo Izen (thebombzen)
+ *
+ * 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 JPEG XL Demuxer
+ * @see ISO/IEC 18181-1 and 18181-2
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+#define BITSTREAM_READER_LE
+#include "libavcodec/get_bits.h"
+
+#include "libavutil/intreadwrite.h"
+#include "libavutil/opt.h"
+
+#include "avformat.h"
+#include "internal.h"
+#include "jpegxl_probe.h"
+
+typedef struct JXLAnimDemuxContext {
+    AVBufferRef *initial;
+} JXLAnimDemuxContext;
+
+/*
+ * copies as much of the codestream into the buffer as possible
+ * pass a shorter buflen to request less
+ * returns the number of bytes consumed from input, may be greater than input_len
+ * if the input doesn't end on an ISOBMFF-box boundary
+ */
+static int jpegxl_collect_codestream_header(const uint8_t *input_buffer, int input_len, uint8_t *buffer, int buflen, int *copied) {
+    const uint8_t *b = input_buffer;
+    *copied = 0;
+
+    while (1) {
+        uint64_t size;
+        uint32_t tag;
+        int head_size = 8;
+
+        if (b - input_buffer >= input_len - 16)
+            break;
+
+        size = AV_RB32(b);
+        b += 4;
+        if (size == 1) {
+            size = AV_RB64(b);
+            b += 8;
+            head_size = 16;
+        }
+        /* invalid ISOBMFF size */
+        if (size > 0 && size <= head_size)
+            return AVERROR_INVALIDDATA;
+        if (size > 0)
+            size -= head_size;
+
+        tag = AV_RL32(b);
+        b += 4;
+        if (tag == MKTAG('j', 'x', 'l', 'p')) {
+            b += 4;
+            size -= 4;
+        }
+
+        if (tag == MKTAG('j', 'x', 'l', 'c') || tag == MKTAG('j', 'x', 'l', 'p')) {
+            /*
+             * size = 0 means "until EOF". this is legal but uncommon
+             * here we just set it to the remaining size of the probe buffer
+             * which at this point should always be nonnegative
+             */
+            if (size == 0 || size > input_len - (b - input_buffer))
+                size = input_len - (b - input_buffer);
+
+            if (size > buflen - *copied)
+                size = buflen - *copied;
+            /*
+             * arbitrary chunking of the payload makes this memcpy hard to avoid
+             * in practice this will only be performed one or two times at most
+             */
+            memcpy(buffer + *copied, b, size);
+            *copied += size;
+        }
+        b += size;
+        if (b >= input_buffer + input_len || *copied >= buflen)
+            break;
+    }
+
+    return b - input_buffer;
+}
+
+static int jpegxl_anim_probe(const AVProbeData *p)
+{
+    uint8_t buffer[4096];
+    int copied;
+
+    /* this is a raw codestream */
+    if (AV_RL16(p->buf) == FF_JPEGXL_CODESTREAM_SIGNATURE_LE) {
+        if (ff_jpegxl_verify_codestream_header(p->buf, p->buf_size, 1) >= 1)
+            return AVPROBE_SCORE_MAX;
+
+        return 0;
+    }
+
+    /* not a JPEG XL file at all */
+    if (AV_RL64(p->buf) != FF_JPEGXL_CONTAINER_SIGNATURE_LE)
+        return 0;
+
+    if (jpegxl_collect_codestream_header(p->buf, p->buf_size, buffer, sizeof(buffer), &copied) <= 0 || copied <= 0)
+        return 0;
+
+    if (ff_jpegxl_verify_codestream_header(buffer, copied, 0) >= 1)
+        return AVPROBE_SCORE_MAX;
+
+    return 0;
+}
+
+static int jpegxl_anim_read_header(AVFormatContext *s)
+{
+    JXLAnimDemuxContext *ctx = s->priv_data;
+    AVIOContext *pb = s->pb;
+    AVStream *st;
+    int offset = 0;
+    uint8_t head[256];
+    int headsize = 0;
+    int ctrl;
+    AVRational tb;
+    GetBitContext gbi, *gb = &gbi;
+
+    uint64_t sig16 = avio_rl16(pb);
+    if (sig16 == FF_JPEGXL_CODESTREAM_SIGNATURE_LE) {
+        AV_WL16(head, sig16);
+        headsize = avio_read(s->pb, head + 2, sizeof(head) - 2);
+        if (headsize < 0)
+            return headsize;
+        headsize += 2;
+        ctx->initial = av_buffer_alloc(headsize);
+        if (!ctx->initial)
+            return AVERROR(ENOMEM);
+        memcpy(ctx->initial->data, head, headsize);
+    } else {
+        uint64_t sig64 = avio_rl64(pb);
+        sig64 = (sig64 << 16) | sig16;
+        if (sig64 != FF_JPEGXL_CONTAINER_SIGNATURE_LE)
+            return AVERROR_INVALIDDATA;
+        avio_skip(pb, 2); // first box always 12 bytes
+        while (1) {
+            int copied;
+            uint8_t buf[4096];
+            int read = avio_read(pb, buf, sizeof(buf));
+            if (read < 0)
+                return read;
+            if (!ctx->initial) {
+                ctx->initial = av_buffer_alloc(read + 12);
+                if (!ctx->initial)
+                    return AVERROR(ENOMEM);
+                AV_WL64(ctx->initial->data, FF_JPEGXL_CONTAINER_SIGNATURE_LE);
+                AV_WL32(ctx->initial->data + 8, 0x0a870a0d);
+            } else {
+                /* this only should be happening zero or one times in practice */
+                if (av_buffer_realloc(&ctx->initial, ctx->initial->size + read) < 0)
+                    return AVERROR(ENOMEM);
+            }
+            jpegxl_collect_codestream_header(buf, read, head + headsize, sizeof(head) - headsize, &copied);
+            memcpy(ctx->initial->data + (ctx->initial->size - read), buf, read);
+            headsize += copied;
+            if (headsize >= sizeof(head) || read < sizeof(buf))
+                break;
+        }
+    }
+    /* offset in bits of the animation header */
+    offset = ff_jpegxl_verify_codestream_header(head, headsize, 0);
+    if (offset <= 0)
+        return AVERROR_INVALIDDATA;
+    if (init_get_bits8(gb, head, headsize) < 0)
+        return AVERROR_INVALIDDATA;
+    skip_bits_long(gb, offset);
+
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
+    st->codecpar->codec_id   = AV_CODEC_ID_JPEGXL;
+    ctrl = get_bits(gb, 2);
+    tb.den = (const uint32_t[]){100, 1000, 1, 1}[ctrl] + get_bits_long(gb, (const uint32_t[]){0, 0, 10, 30}[ctrl]);
+    ctrl = get_bits(gb, 2);
+    tb.num = (const uint32_t[]){1, 1001, 1, 1}[ctrl] + get_bits_long(gb, (const uint32_t[]){0, 0, 8, 10}[ctrl]);
+    avpriv_set_pts_info(st, 1, tb.num, tb.den);
+
+    return 0;
+}
+
+/* the decoder requires the full input file as a single packet */
+static int jpegxl_anim_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    JXLAnimDemuxContext *ctx = s->priv_data;
+    AVIOContext *pb = s->pb;
+    int ret;
+    int64_t size;
+    size_t offset = 0;
+
+    if ((size = avio_size(pb)) < 0)
+        return size;
+
+    /* animated JXL this big should not exist */
+    if (size > INT_MAX)
+        return AVERROR_INVALIDDATA;
+
+    if (ctx->initial && size < ctx->initial->size)
+        size = ctx->initial->size;
+
+    if ((ret = av_new_packet(pkt, size) < 0))
+        return ret;
+
+    if (ctx->initial) {
+        offset = ctx->initial->size;
+        memcpy(pkt->data, ctx->initial->data, offset);
+        av_buffer_unref(&ctx->initial);
+    }
+
+    if ((ret = avio_read(pb, pkt->data + offset, size - offset)) < 0)
+        return ret;
+
+    return 0;
+}
+
+static int jpegxl_anim_close(AVFormatContext *s)
+{
+    JXLAnimDemuxContext *ctx = s->priv_data;
+    if (ctx->initial)
+        av_buffer_unref(&ctx->initial);
+
+    return 0;
+}
+
+const AVInputFormat ff_jpegxl_anim_demuxer = {
+    .name           = "jpegxl_anim",
+    .long_name      = NULL_IF_CONFIG_SMALL("Animated JPEG XL"),
+    .priv_data_size = sizeof(JXLAnimDemuxContext),
+    .read_probe     = jpegxl_anim_probe,
+    .read_header    = jpegxl_anim_read_header,
+    .read_packet    = jpegxl_anim_read_packet,
+    .read_close     = jpegxl_anim_close,
+    .flags_internal = FF_FMT_INIT_CLEANUP,
+    .flags          = AVFMT_GENERIC_INDEX,
+    .mime_type      = "image/jxl",
+    .extensions     = "jxl",
+};

libavformat/jpegxl_probe.c

@@ -208,7 +208,7 @@ static void jpegxl_skip_bit_depth(GetBitContext *gb)
  * validate a Jpeg XL Extra Channel Info bundle
  * @return >= 0 upon valid, < 0 upon invalid
  */
-static int jpegxl_read_extra_channel_info(GetBitContext *gb)
+static int jpegxl_read_extra_channel_info(GetBitContext *gb, int validate_level)
 {
     int all_default = jxl_bits(1);
     uint32_t type, name_len = 0;
@@ -217,7 +217,7 @@ static int jpegxl_read_extra_channel_info(GetBitContext *gb)
         type = jxl_enum();
         if (type > 63)
             return -1; /* enum types cannot be 64+ */
-        if (type == FF_JPEGXL_CT_BLACK)
+        if (type == FF_JPEGXL_CT_BLACK && validate_level)
             return -1;
         jpegxl_skip_bit_depth(gb);
         jxl_u32(0, 3, 4, 1, 0, 0, 0, 3); /* dim-shift */
@@ -242,12 +242,12 @@ static int jpegxl_read_extra_channel_info(GetBitContext *gb)
     return 0;
 }
 
-/* verify that a codestream header is valid */
-int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
+int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen, int validate_level)
 {
     GetBitContext gbi, *gb = &gbi;
     int all_default, extra_fields = 0;
     int xyb_encoded = 1, have_icc_profile = 0;
+    int animation_offset = 0;
     uint32_t num_extra_channels;
     uint64_t extensions;
     int ret;
@@ -259,7 +259,7 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
     if (jxl_bits(16) != FF_JPEGXL_CODESTREAM_SIGNATURE_LE)
         return -1;
 
-    if (jpegxl_read_size_header(gb) < 0)
+    if (jpegxl_read_size_header(gb) < 0 && validate_level)
         return -1;
 
     all_default = jxl_bits(1);
@@ -285,6 +285,7 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
 
         /* animation header */
         if (jxl_bits(1)) {
+            animation_offset = get_bits_count(gb);
             jxl_u32(100, 1000, 1, 1, 0, 0, 10, 30);
             jxl_u32(1, 1001, 1, 1, 0, 0, 8, 10);
             jxl_u32(0, 0, 0, 0, 0, 3, 16, 32);
@@ -296,14 +297,14 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
         jpegxl_skip_bit_depth(gb);
 
         /* modular_16bit_buffers must equal 1 */
-        if (!jxl_bits(1))
+        if (!jxl_bits(1) && validate_level)
             return -1;
 
         num_extra_channels = jxl_u32(0, 1, 2, 1, 0, 0, 4, 12);
-        if (num_extra_channels > 4)
+        if (num_extra_channels > 4 && validate_level)
             return -1;
         for (uint32_t i = 0; i < num_extra_channels; i++) {
-            if (jpegxl_read_extra_channel_info(gb) < 0)
+            if (jpegxl_read_extra_channel_info(gb, validate_level) < 0)
                 return -1;
         }
 
@@ -392,5 +393,5 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
     if (get_bits_left(gb) < 0)
         return -1;
 
-    return 0;
+    return animation_offset;
 }

libavformat/jpegxl_probe.h

@@ -27,6 +27,11 @@
 #define FF_JPEGXL_CODESTREAM_SIGNATURE_LE 0x0aff
 #define FF_JPEGXL_CONTAINER_SIGNATURE_LE 0x204c584a0c000000
 
-int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen);
+/**
+ * @brief verify that a codestream header is valid
+ * @return Negative upon error, 0 upon verifying that the codestream is not animated,
+ *         and 1 upon verifying that it is animated
+ */
+int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen, int validate_level);
 
 #endif /* AVFORMAT_JPEGXL_PROBE_H */

libavformat/version.h

@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFORMAT_VERSION_MINOR   5
+#define LIBAVFORMAT_VERSION_MINOR   6
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \