((double)encoder_context->brc.framerate[i - 1].num / (double)encoder_context->brc.framerate[i - 1].den);
}
+ if (mfc_context->brc.mode == VA_RC_VBR && encoder_context->brc.target_percentage[i])
+ bitrate = bitrate * encoder_context->brc.target_percentage[i] / 100;
+
if (i == encoder_context->layer.num_layers - 1)
factor = 1.0;
else {
return BRC_NO_HRD_VIOLATION;
}
-int intel_mfc_brc_postpack(struct encode_state *encode_state,
- struct intel_encoder_context *encoder_context,
- int frame_bits)
+static int intel_mfc_brc_postpack_cbr(struct encode_state *encode_state,
+ struct intel_encoder_context *encoder_context,
+ int frame_bits)
{
struct gen6_mfc_context *mfc_context = encoder_context->mfc_context;
gen6_brc_status sts = BRC_NO_HRD_VIOLATION;
return sts;
}
+static int intel_mfc_brc_postpack_vbr(struct encode_state *encode_state,
+ struct intel_encoder_context *encoder_context,
+ int frame_bits)
+{
+ struct gen6_mfc_context *mfc_context = encoder_context->mfc_context;
+ gen6_brc_status sts;
+ VAEncSliceParameterBufferH264 *pSliceParameter = (VAEncSliceParameterBufferH264 *)encode_state->slice_params_ext[0]->buffer;
+ int slice_type = intel_avc_enc_slice_type_fixup(pSliceParameter->slice_type);
+ int *qp = mfc_context->brc.qp_prime_y[0];
+ int min_qp = MAX(1, encoder_context->brc.min_qp);
+ int qp_delta, large_frame_adjustment;
+
+ // This implements a simple reactive VBR rate control mode for single-layer H.264. The primary
+ // aim here is to avoid the problematic behaviour that the CBR rate controller displays on
+ // scene changes, where the QP can get pushed up by a large amount in a short period and
+ // compromise the quality of following frames to a very visible degree.
+ // The main idea, then, is to try to keep the HRD buffering above the target level most of the
+ // time, so that when a large frame is generated (on a scene change or when the stream
+ // complexity increases) we have plenty of slack to be able to encode the more difficult region
+ // without compromising quality immediately on the following frames. It is optimistic about
+ // the complexity of future frames, so even after generating one or more large frames on a
+ // significant change it will try to keep the QP at its current level until the HRD buffer
+ // bounds force a change to maintain the intended rate.
+
+ sts = intel_mfc_update_hrd(encode_state, encoder_context, frame_bits);
+
+ // This adjustment is applied to increase the QP by more than we normally would if a very
+ // large frame is encountered and we are in danger of running out of slack.
+ large_frame_adjustment = rint(2.0 * log(frame_bits / mfc_context->brc.target_frame_size[0][slice_type]));
+
+ if (sts == BRC_UNDERFLOW) {
+ // The frame is far too big and we don't have the bits available to send it, so it will
+ // have to be re-encoded at a higher QP.
+ qp_delta = +2;
+ if (frame_bits > mfc_context->brc.target_frame_size[0][slice_type])
+ qp_delta += large_frame_adjustment;
+ } else if (sts == BRC_OVERFLOW) {
+ // The frame is very small and we are now overflowing the HRD buffer. Currently this case
+ // does not occur because we ignore overflow in VBR mode.
+ assert(0 && "Overflow in VBR mode");
+ } else if (frame_bits <= mfc_context->brc.target_frame_size[0][slice_type]) {
+ // The frame is smaller than the average size expected for this frame type.
+ if (mfc_context->hrd.current_buffer_fullness[0] >
+ (mfc_context->hrd.target_buffer_fullness[0] + mfc_context->hrd.buffer_size[0]) / 2.0) {
+ // We currently have lots of bits available, so decrease the QP slightly for the next
+ // frame.
+ qp_delta = -1;
+ } else {
+ // The HRD buffer fullness is increasing, so do nothing. (We may be under the target
+ // level here, but are moving in the right direction.)
+ qp_delta = 0;
+ }
+ } else {
+ // The frame is larger than the average size expected for this frame type.
+ if (mfc_context->hrd.current_buffer_fullness[0] > mfc_context->hrd.target_buffer_fullness[0]) {
+ // We are currently over the target level, so do nothing.
+ qp_delta = 0;
+ } else if (mfc_context->hrd.current_buffer_fullness[0] > mfc_context->hrd.target_buffer_fullness[0] / 2.0) {
+ // We are under the target level, but not critically. Increase the QP by one step if
+ // continuing like this would underflow soon (currently within one second).
+ if (mfc_context->hrd.current_buffer_fullness[0] /
+ (double)(frame_bits - mfc_context->brc.target_frame_size[0][slice_type] + 1) <
+ ((double)encoder_context->brc.framerate[0].num / (double)encoder_context->brc.framerate[0].den))
+ qp_delta = +1;
+ else
+ qp_delta = 0;
+ } else {
+ // We are a long way under the target level. Always increase the QP, possibly by a
+ // larger amount dependent on how big the frame we just made actually was.
+ qp_delta = +1 + large_frame_adjustment;
+ }
+ }
+
+ switch (slice_type) {
+ case SLICE_TYPE_I:
+ qp[SLICE_TYPE_I] += qp_delta;
+ qp[SLICE_TYPE_P] = qp[SLICE_TYPE_I] + BRC_I_P_QP_DIFF;
+ qp[SLICE_TYPE_B] = qp[SLICE_TYPE_I] + BRC_I_B_QP_DIFF;
+ break;
+ case SLICE_TYPE_P:
+ qp[SLICE_TYPE_P] += qp_delta;
+ qp[SLICE_TYPE_I] = qp[SLICE_TYPE_P] - BRC_I_P_QP_DIFF;
+ qp[SLICE_TYPE_B] = qp[SLICE_TYPE_P] + BRC_P_B_QP_DIFF;
+ break;
+ case SLICE_TYPE_B:
+ qp[SLICE_TYPE_B] += qp_delta;
+ qp[SLICE_TYPE_I] = qp[SLICE_TYPE_B] - BRC_I_B_QP_DIFF;
+ qp[SLICE_TYPE_P] = qp[SLICE_TYPE_B] - BRC_P_B_QP_DIFF;
+ break;
+ }
+ BRC_CLIP(mfc_context->brc.qp_prime_y[0][SLICE_TYPE_I], min_qp, 51);
+ BRC_CLIP(mfc_context->brc.qp_prime_y[0][SLICE_TYPE_P], min_qp, 51);
+ BRC_CLIP(mfc_context->brc.qp_prime_y[0][SLICE_TYPE_B], min_qp, 51);
+
+ if (sts == BRC_UNDERFLOW && qp[slice_type] == 51)
+ sts = BRC_UNDERFLOW_WITH_MAX_QP;
+ if (sts == BRC_OVERFLOW && qp[slice_type] == min_qp)
+ sts = BRC_OVERFLOW_WITH_MIN_QP;
+
+ return sts;
+}
+
+int intel_mfc_brc_postpack(struct encode_state *encode_state,
+ struct intel_encoder_context *encoder_context,
+ int frame_bits)
+{
+ switch (encoder_context->rate_control_mode) {
+ case VA_RC_CBR:
+ return intel_mfc_brc_postpack_cbr(encode_state, encoder_context, frame_bits);
+ case VA_RC_VBR:
+ return intel_mfc_brc_postpack_vbr(encode_state, encoder_context, frame_bits);
+ }
+ assert(0 && "Invalid RC mode");
+}
+
static void intel_mfc_hrd_context_init(struct encode_state *encode_state,
struct intel_encoder_context *encoder_context)
{
encoder_context->codec != CODEC_H264_MVC)
return;
- if (rate_control_mode == VA_RC_CBR) {
+ if (rate_control_mode != VA_RC_CQP) {
/*Programing bit rate control */
if (encoder_context->brc.need_reset) {
intel_mfc_bit_rate_control_context_init(encode_state, encoder_context);
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