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Fixed encode of trailing B frames

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In case a P frame was marked as the last frame to encode, the B frames
previous to it in the same gop were not getting encoded. This is fixed now.

Bug: 22860270

Change-Id: I871f2a1d52b8db9ee75426b00287b58203586f23
This commit is contained in:
Harinarayanan K K 2015-06-29 15:04:53 +05:30 • committed by Marco Nelissen
parent b0aadd0c45
commit 01168dc07e
1 changed files with 80 additions and 0 deletions
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80
encoder/ih264e_utils.c
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@ -347,6 +347,86 @@ WORD32 ih264e_input_queue_update(codec_t *ps_codec,
ps_enc_buff->pv_pic_info = ps_inp_buf->pv_pic_info;
ps_enc_buff->u4_pic_info_type = ps_inp_buf->u4_pic_info_type;
/* Special case for encoding trailing B frames
*
* In encoding streams with B frames it may happen that we have a B frame
* at the end without a P/I frame after it. Hence when we are dequeing from
* the RC, it will return the P frame [next in display order but before in
* encoding order] first. Since the dequeue happens for an invalid frame we
* will get a frame with null buff and set u4_is_last. Hence lib with return
* last frame flag at this point and will stop encoding.
*
* Since for the last B frame, we does not have the forward ref frame
* it makes sense to force it into P.
*
* To solve this, in case the current frame is P and if the last frame flag
* is set, we need to see if there is and pending B frames. If there are any,
* we should just encode that picture as the current P frame and set
* that B frame as the last frame. Hence the encoder will terminate naturally
* once that B-frame is encoded after all the in between frames.
*
* Since we cannot touch RC stack directly, the option of actually swapping
* frames in RC is ruled out. We have to modify the as_inp_list to simulate
* such a behavior by RC. We can do that by
* 1) Search through as_inp_list to locate the largest u4_timestamp_low less
* than current u4_timestamp_low. This will give us the last B frame before
* the current P frame. Note that this will handle pre encode skip too since
* queue happens after pre enc skip.
* 2) Swap the position in as_inp_list. Hence now the last B frame is
* encoded as P frame. And the new last B frame will have u4_is_last
* set so that encoder will end naturally once we reached that B frame
* or any subsequent frame. Also the current GOP will have 1 less B frame
* Since we are swapping, the poc will also be in-order.
* 3) In case we have an IPP stream, the result of our search will be an
* I/P frame which is already encoded. Thus swap and encode will result
* in encoding of duplicate frames. Hence to avoid this we will only
* have this work around in case of u4_num_bframes > 0.
*
* In case we have forced an I/IDR frame In between this P frame and
* the last B frame -> This cannot happen as the current P frame is
* supposed to have u4_is_last set. Thus forcing an I/ IDR after this
* is illogical.
*
* In cae if we have forced an I such that the frame just before last frame
* in is I/P -> This case will never arise. Since we have a closed GOP now,
* once we force an I, the gop gets reset, hence there will be a B between
* I/P and I/P.
*/
if (ps_enc_buff->u4_is_last && (ps_codec->pic_type == PIC_P)
&& ps_codec->s_cfg.u4_num_bframes && (ps_codec->i4_poc > 1))
{
UWORD32 u4_cntr, u4_lst_bframe;
inp_buf_t *ps_swap_buff, *ps_inp_list, *ps_cur_pic;
u4_cntr = (u4_pic_id + 1) % MAX_NUM_BFRAMES;
u4_lst_bframe = u4_pic_id ? ((u4_pic_id - 1) % MAX_NUM_BFRAMES) : (MAX_NUM_BFRAMES - 1);
ps_inp_list = &ps_codec->as_inp_list[0];
ps_cur_pic = &ps_inp_list[u4_pic_id % MAX_NUM_BFRAMES];
/* Now search the pic in most recent past to current frame */
for(; u4_cntr != (u4_pic_id % MAX_NUM_BFRAMES);
u4_cntr = ((u4_cntr + 1) % MAX_NUM_BFRAMES))
{
if ( (ps_inp_list[u4_cntr].u4_timestamp_low <= ps_cur_pic->u4_timestamp_low) &&
(ps_inp_list[u4_cntr].u4_timestamp_high <= ps_cur_pic->u4_timestamp_high) &&
(ps_inp_list[u4_cntr].u4_timestamp_low >= ps_inp_list[u4_lst_bframe].u4_timestamp_low) &&
(ps_inp_list[u4_cntr].u4_timestamp_high >= ps_inp_list[u4_lst_bframe].u4_timestamp_high))
{
u4_lst_bframe = u4_cntr;
}
}
ps_swap_buff = &(ps_codec->as_inp_list[u4_lst_bframe]);
/* copy the last B buffer to output */
*ps_enc_buff = *ps_swap_buff;
/* Store the current buf into the queue in place of last B buf */
*ps_swap_buff = *ps_inp_buf;
}
if (ps_enc_buff->u4_is_last)
{
ps_codec->pic_type = PIC_NA;