[FFmpeg-devel] [PATCH] libavcodec/libx264.c: Fix chromaoffset of libx264 doesn't work

[Takio Yamaoka]

An initial value of `AVCodecContext::chromaoffset` is zero,
then it causes to block `-chromaoffset` setting as result.
In addition, even though a negative number of `chromaoffset`
is meaningful, `X264Context::chroma_offset` is initialized
with `-1` as no setting and ignored if it is negative number.

To fix above, it changes ...
- a value of `X264Context::chroma_offset` to 0 as no setting
    - due to x264's default value
- conditional statement to import `-chromaoffset`
---
 libavcodec/libx264.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
index 7bbeab7d4c..347d29df27 100644
--- a/libavcodec/libx264.c
+++ b/libavcodec/libx264.c
@@ -681,11 +681,11 @@ static av_cold int X264_init(AVCodecContext *avctx)
 
 #if FF_API_PRIVATE_OPT
 FF_DISABLE_DEPRECATION_WARNINGS
-    if (avctx->chromaoffset >= 0)
+    if (avctx->chromaoffset)
         x4->chroma_offset = avctx->chromaoffset;
 FF_ENABLE_DEPRECATION_WARNINGS
 #endif
-    if (x4->chroma_offset >= 0)
+    if (x4->chroma_offset)
         x4->params.analyse.i_chroma_qp_offset = x4->chroma_offset;
 
     if (avctx->gop_size >= 0)
@@ -1140,7 +1140,7 @@ static const AVOption options[] = {
     { "vlc",              NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 },  INT_MIN, INT_MAX, VE, "coder" },
     { "ac",               NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 },  INT_MIN, INT_MAX, VE, "coder" },
     { "b_strategy",   "Strategy to choose between I/P/B-frames",          OFFSET(b_frame_strategy), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 2, VE },
-    { "chromaoffset", "QP difference between chroma and luma",            OFFSET(chroma_offset), AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX, VE },
+    { "chromaoffset", "QP difference between chroma and luma",            OFFSET(chroma_offset), AV_OPT_TYPE_INT, { .i64 = 0 }, INT_MIN, INT_MAX, VE },
     { "sc_threshold", "Scene change threshold",                           OFFSET(scenechange_threshold), AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX, VE },
     { "noise_reduction", "Noise reduction",                               OFFSET(noise_reduction), AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX, VE },
 
-- 
2.17.1