[FFmpeg-devel] [PATCH 1/2] avcodec/videotoolboxenc: fix undefined behavior with rc_max_rate=0

[Thomas Guillem]

On macOS, a zero rc_max_rate cause an error from
VTSessionSetProperty(kVTCompressionPropertyKey_DataRateLimits).

on iOS (depending on device/version), a zero rc_max_rate cause invalid
arguments from the vtenc_output_callback after few frames and then a crash
within the VideoToolbox library.
---
 libavcodec/videotoolboxenc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/videotoolboxenc.c b/libavcodec/videotoolboxenc.c
index ac847358ab..aa9aae7e05 100644
--- a/libavcodec/videotoolboxenc.c
+++ b/libavcodec/videotoolboxenc.c
@@ -1019,6 +1019,7 @@ static int vtenc_create_encoder(AVCodecContext   *avctx,
 
     if (vtctx->codec_id == AV_CODEC_ID_H264) {
         // kVTCompressionPropertyKey_DataRateLimits is not available for HEVC
+        if (max_rate > 0) {
         bytes_per_second_value = max_rate >> 3;
         bytes_per_second = CFNumberCreate(kCFAllocatorDefault,
                                           kCFNumberSInt64Type,
@@ -1058,6 +1059,7 @@ static int vtenc_create_encoder(AVCodecContext   *avctx,
             av_log(avctx, AV_LOG_ERROR, "Error setting max bitrate property: %d\n", status);
             return AVERROR_EXTERNAL;
         }
+        }
 
         if (profile_level) {
             status = VTSessionSetProperty(vtctx->session,
-- 
2.18.0