[FFmpeg-devel] [PATCH] swfdec: support compressed swf.

[Clément Bœsch]

---
 libavformat/swf.h    |   11 ++++++++
 libavformat/swfdec.c |   72 +++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/libavformat/swf.h b/libavformat/swf.h
index affebe9..8a99c96 100644
--- a/libavformat/swf.h
+++ b/libavformat/swf.h
@@ -23,6 +23,10 @@
 #ifndef AVFORMAT_SWF_H
 #define AVFORMAT_SWF_H
 
+#if CONFIG_ZLIB
+#include <zlib.h>
+#endif
+
 #include "libavutil/fifo.h"
 #include "avformat.h"
 #include "avio.h"
@@ -76,6 +80,13 @@ typedef struct {
     int tag;
     AVFifoBuffer *audio_fifo;
     AVCodecContext *audio_enc, *video_enc;
+#if CONFIG_ZLIB
+    AVIOContext *zpb;
+#define ZBUF_SIZE 4096
+    uint8_t *zbuf_in;
+    uint8_t *zbuf_out;
+    z_stream zstream;
+#endif
 } SWFContext;
 
 static const AVCodecTag swf_codec_tags[] = {
diff --git a/libavformat/swfdec.c b/libavformat/swfdec.c
index 4a2c3d5..64e44f1 100644
--- a/libavformat/swfdec.c
+++ b/libavformat/swfdec.c
@@ -52,6 +52,35 @@ static int swf_probe(AVProbeData *p)
         return 0;
 }
 
+#if CONFIG_ZLIB
+static int zlib_refill(void *opaque, uint8_t *buf, int buf_size)
+{
+    AVFormatContext *s = opaque;
+    SWFContext *swf = s->priv_data;
+    z_stream *z = &swf->zstream;
+
+retry:
+    if (!z->avail_in) {
+        int n = avio_read(s->pb, swf->zbuf_in, ZBUF_SIZE);
+        if (n <= 0)
+            return n;
+        z->next_in  = swf->zbuf_in;
+        z->avail_in = n;
+    }
+
+    z->next_out  = buf;
+    z->avail_out = buf_size;
+
+    if (inflate(z, Z_NO_FLUSH) < 0)
+        return AVERROR(EINVAL);
+
+    if (buf_size - z->avail_out == 0)
+        goto retry;
+
+    return buf_size - z->avail_out;
+}
+#endif
+
 static int swf_read_header(AVFormatContext *s)
 {
     SWFContext *swf = s->priv_data;
@@ -59,14 +88,29 @@ static int swf_read_header(AVFormatContext *s)
     int nbits, len, tag;
 
     tag = avio_rb32(pb) & 0xffffff00;
+    avio_rl32(pb);
 
     if (tag == MKBETAG('C', 'W', 'S', 0)) {
-        av_log(s, AV_LOG_ERROR, "Compressed SWF format not supported\n");
+        av_log(s, AV_LOG_INFO, "SWF compressed file detected\n");
+#if CONFIG_ZLIB
+        swf->zbuf_in  = av_malloc(ZBUF_SIZE);
+        swf->zbuf_out = av_malloc(ZBUF_SIZE);
+        swf->zpb = avio_alloc_context(swf->zbuf_out, ZBUF_SIZE, 0, s,
+                                      zlib_refill, NULL, NULL);
+        if (!swf->zpb)
+            return AVERROR(ENOMEM);
+        swf->zpb->seekable = 0;
+        if (inflateInit(&swf->zstream) != Z_OK) {
+            av_log(s, AV_LOG_ERROR, "Unable to init zlib context\n");
+            return AVERROR(EINVAL);
+        }
+        pb = swf->zpb;
+#else
+        av_log(s, AV_LOG_ERROR, "zlib support is required to read SWF compressed files\n");
         return AVERROR(EIO);
-    }
-    if (tag != MKBETAG('F', 'W', 'S', 0))
+#endif
+    } else if (tag != MKBETAG('F', 'W', 'S', 0))
         return AVERROR(EIO);
-    avio_rl32(pb);
     /* skip rectangle size */
     nbits = avio_r8(pb) >> 3;
     len = (4 * nbits - 3 + 7) / 8;
@@ -86,6 +130,11 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
     AVStream *vst = NULL, *ast = NULL, *st = 0;
     int tag, len, i, frame, v, res;
 
+#if CONFIG_ZLIB
+    if (swf->zpb)
+        pb = swf->zpb;
+#endif
+
     for(;;) {
         uint64_t pos = avio_tell(pb);
         tag = get_swf_tag(pb, &len);
@@ -209,6 +258,18 @@ static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
     }
 }
 
+#if CONFIG_ZLIB
+static av_cold int swf_read_close(AVFormatContext *avctx)
+{
+    SWFContext *s = avctx->priv_data;
+    inflateEnd(&s->zstream);
+    av_freep(&s->zbuf_in);
+    av_freep(&s->zbuf_out);
+    av_freep(&s->zpb);
+    return 0;
+}
+#endif
+
 AVInputFormat ff_swf_demuxer = {
     .name           = "swf",
     .long_name      = NULL_IF_CONFIG_SMALL("Flash format"),
@@ -216,4 +277,7 @@ AVInputFormat ff_swf_demuxer = {
     .read_probe     = swf_probe,
     .read_header    = swf_read_header,
     .read_packet    = swf_read_packet,
+#if CONFIG_ZLIB
+    .read_close     = swf_read_close,
+#endif
 };
-- 
1.7.9.5