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encoder: h264: fix bitrate encoding for HRD conformance.

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Round down the calculated, or supplied, bitrate (kbps) into a multiple
of the HRD bitrate scale factor. Use a bitrate scale factor of 64 so
that to have less losses in precision. Likewise, don't round up because
that could be a strict constraint imposed by the user.
This commit is contained in:
Gwenole Beauchesne 2014-01-22 14:43:24 +01:00
parent 4c04a1bc88
commit 9d42c86422
1 changed files with 33 additions and 19 deletions
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52
gst-libs/gst/vaapi/gstvaapiencoder_h264.c
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@ -37,6 +37,9 @@
/* Define the maximum IDR period */
#define MAX_IDR_PERIOD 512
/* Scale factor for bitrate (HRD bit_rate_scale: min = 6) */
#define SX_BITRATE 6
/* Define default rate control mode ("constant-qp") */
#define DEFAULT_RATECONTROL GST_VAAPI_RATECONTROL_CQP
@ -415,12 +418,12 @@ bs_write_sps (GstBitWriter * bs,
/* hrd_parameters */
/* cpb_cnt_minus1 */
WRITE_UE (bs, 0);
WRITE_UINT32 (bs, 4, 4); /* bit_rate_scale */
WRITE_UINT32 (bs, SX_BITRATE - 6, 4); /* bit_rate_scale */
WRITE_UINT32 (bs, 6, 4); /* cpb_size_scale */
for (i = 0; i < 1; ++i) {
/* bit_rate_value_minus1[0] */
WRITE_UE (bs, seq_param->bits_per_second / 1000 - 1);
WRITE_UE (bs, (seq_param->bits_per_second >> SX_BITRATE) - 1);
/* cpb_size_value_minus1[0] */
WRITE_UE (bs, seq_param->bits_per_second / 1000 * 8 - 1);
/* cbr_flag[0] */
@ -581,6 +584,8 @@ struct _GstVaapiEncoderH264
GstBuffer *sps_data;
GstBuffer *pps_data;
guint bitrate_bits; // bitrate (bits)
};
static inline void
@ -744,7 +749,6 @@ static gboolean
ensure_level (GstVaapiEncoderH264 * encoder)
{
const guint cpb_factor = h264_get_cpb_nal_factor (encoder->profile);
const guint bitrate = GST_VAAPI_ENCODER_CAST (encoder)->bitrate * 1000;
const GstVaapiH264LevelLimits *limits_table;
guint i, num_limits, PicSizeMbs, MaxDpbMbs, MaxMBPS;
@ -758,8 +762,8 @@ ensure_level (GstVaapiEncoderH264 * encoder)
const GstVaapiH264LevelLimits *const limits = &limits_table[i];
if (PicSizeMbs <= limits->MaxFS &&
MaxDpbMbs <= limits->MaxDpbMbs &&
MaxMBPS <= limits->MaxMBPS && (!bitrate
|| bitrate <= (limits->MaxBR * cpb_factor)))
MaxMBPS <= limits->MaxMBPS && (!encoder->bitrate_bits
|| encoder->bitrate_bits <= (limits->MaxBR * cpb_factor)))
break;
}
if (i == num_limits)
@ -892,10 +896,8 @@ set_key_frame (GstVaapiEncPicture * picture,
static void
fill_hrd_params (GstVaapiEncoderH264 * encoder, VAEncMiscParameterHRD * hrd)
{
GstVaapiEncoder *const base_encoder = GST_VAAPI_ENCODER_CAST (encoder);
if (base_encoder->bitrate > 0) {
hrd->buffer_size = base_encoder->bitrate * 1000 * 8;
if (encoder->bitrate_bits > 0) {
hrd->buffer_size = encoder->bitrate_bits * 8;
hrd->initial_buffer_fullness = hrd->buffer_size / 2;
} else {
hrd->buffer_size = 0;
@ -1100,7 +1102,6 @@ reference_list_init (GstVaapiEncoderH264 * encoder,
static gboolean
fill_sequence (GstVaapiEncoderH264 * encoder, GstVaapiEncSequence * sequence)
{
GstVaapiEncoder *const base_encoder = GST_VAAPI_ENCODER_CAST (encoder);
VAEncSequenceParameterBufferH264 *const seq_param = sequence->param;
memset (seq_param, 0, sizeof (VAEncSequenceParameterBufferH264));
@ -1108,10 +1109,7 @@ fill_sequence (GstVaapiEncoderH264 * encoder, GstVaapiEncSequence * sequence)
seq_param->level_idc = encoder->level_idc;
seq_param->intra_period = GST_VAAPI_ENCODER_KEYFRAME_PERIOD (encoder);
seq_param->ip_period = 1 + encoder->num_bframes;
if (base_encoder->bitrate > 0)
seq_param->bits_per_second = base_encoder->bitrate * 1000;
else
seq_param->bits_per_second = 0;
seq_param->bits_per_second = encoder->bitrate_bits;
seq_param->max_num_ref_frames = encoder->max_ref_frames;
seq_param->picture_width_in_mbs = encoder->mb_width;
@ -1418,7 +1416,6 @@ error_create_packed_seq_hdr:
static gboolean
ensure_misc_params (GstVaapiEncoderH264 * encoder, GstVaapiEncPicture * picture)
{
GstVaapiEncoder *const base_encoder = GST_VAAPI_ENCODER_CAST (encoder);
GstVaapiEncMiscParam *misc = NULL;
VAEncMiscParameterRateControl *rate_control;
@ -1440,10 +1437,7 @@ ensure_misc_params (GstVaapiEncoderH264 * encoder, GstVaapiEncPicture * picture)
return FALSE;
rate_control = misc->data;
memset (rate_control, 0, sizeof (VAEncMiscParameterRateControl));
if (base_encoder->bitrate)
rate_control->bits_per_second = base_encoder->bitrate * 1000;
else
rate_control->bits_per_second = 0;
rate_control->bits_per_second = encoder->bitrate_bits;
rate_control->target_percentage = 70;
rate_control->window_size = 500;
rate_control->initial_qp = encoder->init_qp;
@ -1505,6 +1499,25 @@ ensure_slices (GstVaapiEncoderH264 * encoder, GstVaapiEncPicture * picture)
return TRUE;
}
/* Normalizes bitrate (and CPB size) for HRD conformance */
static void
ensure_bitrate_hrd (GstVaapiEncoderH264 * encoder)
{
GstVaapiEncoder *const base_encoder = GST_VAAPI_ENCODER_CAST (encoder);
guint bitrate;
if (!base_encoder->bitrate) {
encoder->bitrate_bits = 0;
return;
}
/* Round down bitrate. This is a hard limit mandated by the user */
g_assert (SX_BITRATE >= 6);
bitrate = (base_encoder->bitrate * 1000) & ~((1U << SX_BITRATE) - 1);
GST_DEBUG ("HRD bitrate: %u bits/sec", bitrate);
encoder->bitrate_bits = bitrate;
}
/* Estimates a good enough bitrate if none was supplied */
static void
ensure_bitrate (GstVaapiEncoderH264 * encoder)
@ -1538,6 +1551,7 @@ ensure_bitrate (GstVaapiEncoderH264 * encoder)
base_encoder->bitrate = 0;
break;
}
ensure_bitrate_hrd (encoder);
}
/* Constructs profile and level information based on user-defined limits */