[FFmpeg-devel] [PATCH] Bitmap Brothers JV demuxer

Peter Ross pross
Wed Mar 9 11:45:41 CET 2011


---

On Tue, Mar 08, 2011 at 04:35:54PM +0100, Kostya wrote:
> On Wed, Mar 09, 2011 at 02:10:50AM +1100, Peter Ross wrote:
[..]
> > +static int read_probe(AVProbeData *pd)
> > +{
> > +    if (pd->buf[0] == 'J' && pd->buf[1] == 'V' &&
> > +        !memcmp(pd->buf + 4, MAGIC, FFMIN(strlen(MAGIC), pd->buf_size - 4)))
> > +        return AVPROBE_SCORE_MAX;
> > +    return 0;
> > +}
>
> I think it's wrong to return score_max if you have too small probe buffer not
> to fit all magic string.

Isn't buf_size guaranteed to be at least 32-bytes? So in the worst case, the
memcmp will compare 28 bytes, which is still a strong enough indicator IMHO.

> [...]
>
> BTW, do you initialise state explicitly somewhere?

JvContext.state defaults to zero when priv_data is allocated. In this updated
patch, i've forced the JV_AUDIO state enum to be zero. That way theres no
need to specifically initialise it in decode_init().

> > +            avio_skip(pb, e->size - jvf->audio_size - jvf->video_size - (jvf->palette ? 768 : 0));
>
> Is that guaranteed to be always non-negative?

Noo! Nicely spotted. While all known JV samples have >=0 padding bytes, a fuzzed
file could cause a endless loop here, so its best that to clamp the range.

>
> Nice state machine you have here though.
>
> [the rest rises no comments from me]

Thanks for the prompt review.

 libavformat/Makefile     |    1 +
 libavformat/allformats.c |    1 +
 libavformat/jvdec.c      |  220 ++++++++++++++++++++++++++++++++++++++++++++++
 libavformat/version.h    |    2 +-
 4 files changed, 223 insertions(+), 1 deletions(-)
 create mode 100644 libavformat/jvdec.c

diff --git a/libavformat/Makefile b/libavformat/Makefile
index eb9ca49..4eb1620 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -110,6 +110,7 @@ OBJS-$(CONFIG_ISS_DEMUXER)               += iss.o
 OBJS-$(CONFIG_IV8_DEMUXER)               += iv8.o
 OBJS-$(CONFIG_IVF_DEMUXER)               += ivfdec.o riff.o
 OBJS-$(CONFIG_IVF_MUXER)                 += ivfenc.o
+OBJS-$(CONFIG_JV_DEMUXER)                += jvdec.o
 OBJS-$(CONFIG_LMLM4_DEMUXER)             += lmlm4.o
 OBJS-$(CONFIG_LXF_DEMUXER)               += lxfdec.o
 OBJS-$(CONFIG_M4V_DEMUXER)               += m4vdec.o rawdec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 562f624..bca968a 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -110,6 +110,7 @@ void av_register_all(void)
     REGISTER_DEMUXER  (ISS, iss);
     REGISTER_DEMUXER  (IV8, iv8);
     REGISTER_MUXDEMUX (IVF, ivf);
+    REGISTER_DEMUXER  (JV, jv);
     REGISTER_DEMUXER  (LMLM4, lmlm4);
     REGISTER_DEMUXER  (LXF, lxf);
     REGISTER_MUXDEMUX (M4V, m4v);
diff --git a/libavformat/jvdec.c b/libavformat/jvdec.c
new file mode 100644
index 0000000..d804ed9
--- /dev/null
+++ b/libavformat/jvdec.c
@@ -0,0 +1,220 @@
+/*
+ * Bitmap Brothers JV demuxer
+ * Copyright (c) 2005, 2011 Peter Ross <pross at xvid.org>
+ *
+ * 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
+ * Bitmap Brothers JV demuxer
+ * @author Peter Ross <pross at xvid.org>
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avformat.h"
+
+typedef struct {
+    int audio_size;    /** audio packet size (bytes) */
+    int video_size;    /** video packet size (bytes) */
+    int palette;       /** frame contains palette change */
+    int video_type;    /** per-frame video compression type */
+} JVFrame;
+
+typedef struct {
+    JVFrame *frames;
+    enum {
+        JV_AUDIO = 0,
+        JV_VIDEO,
+        JV_PADDING
+    } state;
+    int64_t pts;
+} JVDemuxContext;
+
+#define MAGIC " Compression by John M Phillips Copyright (C) 1995 The Bitmap Brothers Ltd."
+
+static int read_probe(AVProbeData *pd)
+{
+    if (pd->buf[0] == 'J' && pd->buf[1] == 'V' &&
+        !memcmp(pd->buf + 4, MAGIC, FFMIN(strlen(MAGIC), pd->buf_size - 4)))
+        return AVPROBE_SCORE_MAX;
+    return 0;
+}
+
+static int read_header(AVFormatContext *s,
+                       AVFormatParameters *ap)
+{
+    JVDemuxContext *jv = s->priv_data;
+    AVIOContext *pb = s->pb;
+    AVStream *vst, *ast;
+    int64_t audio_pts = 0;
+    int64_t offset;
+    int i;
+
+    avio_skip(pb, 80);
+
+    ast = av_new_stream(s, 0);
+    vst = av_new_stream(s, 1);
+    if (!ast || !vst)
+        return AVERROR(ENOMEM);
+
+    vst->codec->codec_type  = CODEC_TYPE_VIDEO;
+    vst->codec->codec_id    = CODEC_ID_JV;
+    vst->codec->codec_tag   = 0; /* no fourcc */
+    vst->codec->width       = avio_rl16(pb);
+    vst->codec->height      = avio_rl16(pb);
+    vst->nb_frames          =
+    ast->nb_index_entries   = avio_rl16(pb);
+    av_set_pts_info(vst, 64, avio_rl16(pb), 1000);
+
+    avio_skip(pb, 4);
+
+    ast->codec->codec_type  = CODEC_TYPE_AUDIO;
+    ast->codec->codec_id    = CODEC_ID_PCM_U8;
+    ast->codec->codec_tag   = 0; /* no fourcc */
+    ast->codec->sample_rate = avio_rl16(pb);
+    ast->codec->channels    = 1;
+    av_set_pts_info(ast, 64, 1, ast->codec->sample_rate);
+
+    avio_skip(pb, 10);
+
+    ast->index_entries = av_malloc(ast->nb_index_entries * sizeof(*ast->index_entries));
+    if (!ast->index_entries)
+        return AVERROR(ENOMEM);
+
+    jv->frames = av_malloc(ast->nb_index_entries * sizeof(JVFrame));
+    if (!jv->frames)
+        return AVERROR(ENOMEM);
+
+    offset = 0x68 + ast->nb_index_entries * 16;
+    for(i = 0; i < ast->nb_index_entries; i++) {
+        AVIndexEntry *e   = ast->index_entries + i;
+        JVFrame      *jvf = jv->frames + i;
+
+        /* total frame size including audio, video, palette data and padding */
+        e->size         = avio_rl32(pb);
+        e->timestamp    = i;
+        e->pos          = offset;
+        offset         += e->size;
+
+        jvf->audio_size = avio_rl32(pb);
+        jvf->video_size = avio_rl32(pb);
+        jvf->palette    = avio_r8(pb);
+        if (avio_r8(pb))
+             av_log(s, AV_LOG_WARNING, "unsupported audio codec\n");
+        jvf->video_type = avio_r8(pb);
+        avio_skip(pb, 1);
+
+        e->timestamp = jvf->audio_size ? audio_pts : AV_NOPTS_VALUE;
+        audio_pts += jvf->audio_size;
+
+        e->flags = jvf->video_type != 1 ? AVINDEX_KEYFRAME : 0;
+    }
+
+    return 0;
+}
+
+static int read_packet(AVFormatContext *s,
+                       AVPacket *pkt)
+{
+    JVDemuxContext *jv = s->priv_data;
+    AVIOContext *pb = s->pb;
+    AVStream *ast = s->streams[0];
+
+    while (!url_feof(s->pb) && jv->pts < ast->nb_index_entries) {
+        const AVIndexEntry *e   = ast->index_entries + jv->pts;
+        const JVFrame      *jvf = jv->frames + jv->pts;
+
+        switch(jv->state) {
+        case JV_AUDIO:
+            jv->state++;
+            if (jvf->audio_size ) {
+                if (av_get_packet(s->pb, pkt, jvf->audio_size) < 0)
+                    return AVERROR(ENOMEM);
+                pkt->stream_index = 0;
+                pkt->pts          = e->timestamp;
+                pkt->flags       |= PKT_FLAG_KEY;
+                return 0;
+            }
+        case JV_VIDEO:
+            jv->state++;
+            if (jvf->video_size || jvf->palette) {
+                int size = jvf->video_size + (jvf->palette ? 768 : 0);
+                if (av_new_packet(pkt, size + 5))
+                    return AVERROR(ENOMEM);
+
+                AV_WL32(pkt->data, jvf->video_size);
+                pkt->data[4]      = jvf->video_type;
+                if (avio_read(pb, pkt->data + 5, size) < 0)
+                    return AVERROR(EIO);
+
+                pkt->size         = size + 5;
+                pkt->stream_index = 1;
+                pkt->pts          = jv->pts;
+                if (jvf->video_type != 1)
+                    pkt->flags |= PKT_FLAG_KEY;
+                return 0;
+            }
+        case JV_PADDING:
+            avio_skip(pb, FFMAX(e->size - jvf->audio_size - jvf->video_size - (jvf->palette ? 768 : 0), 0));
+            jv->state = JV_AUDIO;
+            jv->pts++;
+        }
+    }
+
+    return AVERROR(EIO);
+}
+
+static int read_seek(AVFormatContext *s, int stream_index,
+                     int64_t ts, int flags)
+{
+    JVDemuxContext *jv = s->priv_data;
+    AVStream *ast = s->streams[0];
+    int i;
+
+    if (flags & (AVSEEK_FLAG_BYTE|AVSEEK_FLAG_FRAME))
+        return AVERROR_NOTSUPP;
+
+    switch(stream_index) {
+    case 0:
+        i = av_index_search_timestamp(ast, ts, flags);
+        break;
+    case 1:
+        i = ts;
+        break;
+    default:
+        return 0;
+    }
+
+    if (i < 0 || i >= ast->nb_index_entries)
+        return 0;
+
+    jv->state = JV_AUDIO;
+    jv->pts   = i;
+    avio_seek(s->pb, ast->index_entries[i].pos, SEEK_SET);
+    return 0;
+}
+
+AVInputFormat ff_jv_demuxer = {
+    .name           = "jv",
+    .long_name      = NULL_IF_CONFIG_SMALL("Bitmap Brothers JV"),
+    .priv_data_size = sizeof(JVDemuxContext),
+    .read_probe     = read_probe,
+    .read_header    = read_header,
+    .read_packet    = read_packet,
+    .read_seek      = read_seek,
+};
diff --git a/libavformat/version.h b/libavformat/version.h
index 494cf11..aed8908 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -24,7 +24,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFORMAT_VERSION_MAJOR 52
-#define LIBAVFORMAT_VERSION_MINOR 102
+#define LIBAVFORMAT_VERSION_MINOR 103
 #define LIBAVFORMAT_VERSION_MICRO  0
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
-- 
1.7.1


-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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