[FFmpeg-cvslog] avcodec/cscd: Fix "CamStudio Lossless Codec 1.0" gzip files

[Michael Niedermayer]

ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Sun Sep 10 16:27:02 2023 +0200| [b9bf29ea77b5f3c449959e6a92784a837c97af2e] | committer: Michael Niedermayer

avcodec/cscd: Fix "CamStudio Lossless Codec 1.0" gzip files

Fixes: tickets/10241/cscd_1_0_306_306_gzip.avi

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit ab7d38f970674e6765b5e1adb911c1763b9ce806)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b9bf29ea77b5f3c449959e6a92784a837c97af2e
---

 libavcodec/cscd.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libavcodec/cscd.c b/libavcodec/cscd.c
index d5a20ce04b..af7284ccfb 100644
--- a/libavcodec/cscd.c
+++ b/libavcodec/cscd.c
@@ -71,6 +71,9 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     int buf_size = avpkt->size;
     CamStudioContext *c = avctx->priv_data;
     int ret;
+    int bpp = avctx->bits_per_coded_sample / 8;
+    int bugdelta = FFALIGN(avctx->width * bpp, 4)       * avctx->height
+                 -        (avctx->width     & ~3) * bpp * avctx->height;
 
     if (buf_size < 2) {
         av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
@@ -84,9 +87,6 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     switch ((buf[0] >> 1) & 7) {
     case 0: { // lzo compression
         int outlen = c->decomp_size, inlen = buf_size - 2;
-        int bpp = avctx->bits_per_coded_sample / 8;
-        int bugdelta = FFALIGN(avctx->width * bpp, 4)       * avctx->height
-                     -        (avctx->width     & ~3) * bpp * avctx->height;
         if (av_lzo1x_decode(c->decomp_buf, &outlen, &buf[2], &inlen) || (outlen && outlen != bugdelta)) {
             av_log(avctx, AV_LOG_ERROR, "error during lzo decompression\n");
             return AVERROR_INVALIDDATA;
@@ -96,7 +96,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     case 1: { // zlib compression
 #if CONFIG_ZLIB
         unsigned long dlen = c->decomp_size;
-        if (uncompress(c->decomp_buf, &dlen, &buf[2], buf_size - 2) != Z_OK || dlen != c->decomp_size) {
+        if (uncompress(c->decomp_buf, &dlen, &buf[2], buf_size - 2) != Z_OK || (dlen != c->decomp_size && dlen != c->decomp_size - bugdelta)) {
             av_log(avctx, AV_LOG_ERROR, "error during zlib decompression\n");
             return AVERROR_INVALIDDATA;
         }