We should not arbitrarily decide the maximum B-frame number for all
encoders supported by Libav, each encoder should be able to set its own
limits.
---
libavcodec/avcodec.h | 5 +++++
libavcodec/mpegvideo.h | 2 ++
libavcodec/mpegvideo_enc.c | 6 +++++-
libavcodec/options_table.h | 2 +-
libavcodec/version.h | 3 +++
5 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index a698d33..674fdfe 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -616,7 +616,12 @@ typedef struct RcOverride{
float quality_factor;
} RcOverride;
+#if FF_API_MAX_BFRAMES
+/**
+ * @deprecated there is no libavcodec-wide limit on the number of B-frames
+ */
#define FF_MAX_B_FRAMES 16
+#endif
/* encoding support
These flags can be passed in AVCodecContext.flags before initialization.
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 4970028..c2e8836 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -64,6 +64,8 @@ enum OutputFormat {
#define MAX_PICTURE_COUNT 32
+#define MAX_B_FRAMES 16
+
#define ME_MAP_SIZE 64
#define ME_MAP_SHIFT 3
#define ME_MAP_MV_BITS 11
diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
index 0d7005e..d883711 100644
--- a/libavcodec/mpegvideo_enc.c
+++ b/libavcodec/mpegvideo_enc.c
@@ -290,6 +290,10 @@ av_cold int ff_MPV_encode_init(AVCodecContext *avctx)
s->avctx = avctx;
s->flags = avctx->flags;
s->flags2 = avctx->flags2;
+ if (avctx->max_b_frames > MAX_B_FRAMES) {
+ av_log(avctx, AV_LOG_ERROR, "Too many B-frames requested, maximum "
+ "is %d.\n", MAX_B_FRAMES);
+ }
s->max_b_frames = avctx->max_b_frames;
s->codec_id = avctx->codec->id;
s->strict_std_compliance = avctx->strict_std_compliance;
@@ -1020,7 +1024,7 @@ static int estimate_best_b_count(MpegEncContext *s)
{
AVCodec *codec = avcodec_find_encoder(s->avctx->codec_id);
AVCodecContext *c = avcodec_alloc_context3(NULL);
- AVFrame input[FF_MAX_B_FRAMES + 2];
+ AVFrame input[MAX_B_FRAMES + 2];
const int scale = s->avctx->brd_scale;
int i, j, out_size, p_lambda, b_lambda, lambda2;
int64_t best_rd = INT64_MAX;
diff --git a/libavcodec/options_table.h b/libavcodec/options_table.h
index dbd6007..fe8e72e 100644
--- a/libavcodec/options_table.h
+++ b/libavcodec/options_table.h
@@ -101,7 +101,7 @@ static const AVOption avcodec_options[] = {
{"qmin", "minimum video quantizer scale (VBR)", OFFSET(qmin), AV_OPT_TYPE_INT,
{.i64 = 2 }, -1, 69, V|E},
{"qmax", "maximum video quantizer scale (VBR)", OFFSET(qmax), AV_OPT_TYPE_INT,
{.i64 = 31 }, -1, 69, V|E},
{"qdiff", "maximum difference between the quantizer scales (VBR)",
OFFSET(max_qdiff), AV_OPT_TYPE_INT, {.i64 = 3 }, INT_MIN, INT_MAX, V|E},
-{"bf", "use 'frames' B frames", OFFSET(max_b_frames), AV_OPT_TYPE_INT, {.i64 =
DEFAULT }, -1, FF_MAX_B_FRAMES, V|E},
+{"bf", "use 'frames' B frames", OFFSET(max_b_frames), AV_OPT_TYPE_INT, {.i64 =
DEFAULT }, -1, INT_MAX, V|E},
{"b_qfactor", "QP factor between P- and B-frames", OFFSET(b_quant_factor),
AV_OPT_TYPE_FLOAT, {.dbl = 1.25 }, -FLT_MAX, FLT_MAX, V|E},
{"rc_strategy", "ratecontrol method", OFFSET(rc_strategy), AV_OPT_TYPE_INT,
{.i64 = DEFAULT }, INT_MIN, INT_MAX, V|E},
{"b_strategy", "strategy to choose between I/P/B-frames",
OFFSET(b_frame_strategy), AV_OPT_TYPE_INT, {.i64 = 0 }, INT_MIN, INT_MAX, V|E},
diff --git a/libavcodec/version.h b/libavcodec/version.h
index ffc6e28..04a8b64 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -103,5 +103,8 @@
#ifndef FF_API_MB_TYPE
#define FF_API_MB_TYPE (LIBAVCODEC_VERSION_MAJOR < 56)
#endif
+#ifndef FF_API_MAX_BFRAMES
+#define FF_API_MAX_BFRAMES (LIBAVCODEC_VERSION_MAJOR < 56)
+#endif
#endif /* AVCODEC_VERSION_H */
--
1.7.10.4
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