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h264: fix decoding multiple fields per packet with slice threads 

Since we only know whether a NAL unit corresponds to a new field after
parsing the slice header, this requires reorganizing the calls to slice
parsing, per-slice/field/frame init and actual decoding.

In the previous code, the function for slice header decoding also
immediately started a new field/frame as necessary, so any slices
already queued for decoding would no longer be decodable.

After this patch, we first parse the slice header, and if we determine
that a new field needs to be started we decode all the queued slices.
This commit is contained in:
Anton Khirnov 2016-06-12 14:22:50 +02:00
parent f450cc7bc5
commit 4a9bab3db0
3 changed files with 105 additions and 83 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

129
libavcodec/h264_slice.c
View File

@ -1699,50 +1699,13 @@ static int h264_slice_header_parse(H264SliceContext *sl, const H2645NAL *nal,
return 0;
}
/**
* Decode a slice header.
* This will (re)initialize the decoder and call h264_frame_start() as needed.
*
* @param h h264context
*
* @return 0 if okay, <0 if an error occurred
*/
int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl,
const H2645NAL *nal)
/* do all the per-slice initialization needed before we can start decoding the
* actual MBs */
static int h264_slice_init(H264Context *h, H264SliceContext *sl,
const H2645NAL *nal)
{
int i, j, ret = 0;
ret = h264_slice_header_parse(sl, nal, &h->ps, h->avctx);
if (ret < 0)
return ret;
// discard redundant pictures
if (sl->redundant_pic_count > 0)
return 0;
if (!h->setup_finished) {
if (sl->first_mb_addr == 0) { // FIXME better field boundary detection
if (h->current_slice && h->cur_pic_ptr && FIELD_PICTURE(h)) {
ff_h264_field_end(h, sl, 1);
}
h->current_slice = 0;
if (!h->first_field) {
if (h->cur_pic_ptr && !h->droppable) {
ff_thread_report_progress(&h->cur_pic_ptr->tf, INT_MAX,
h->picture_structure == PICT_BOTTOM_FIELD);
}
h->cur_pic_ptr = NULL;
}
}
if (h->current_slice == 0) {
ret = h264_field_start(h, sl, nal);
if (ret < 0)
return ret;
}
}
if (h->current_slice > 0) {
if (h->ps.pps != (const PPS*)h->ps.pps_list[sl->pps_id]->data) {
av_log(h->avctx, AV_LOG_ERROR, "PPS changed between slices\n");
@ -1886,6 +1849,75 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl,
return 0;
}
int ff_h264_queue_decode_slice(H264Context *h, const H2645NAL *nal)
{
H264SliceContext *sl = h->slice_ctx + h->nb_slice_ctx_queued;
int ret;
sl->gb = nal->gb;
ret = h264_slice_header_parse(sl, nal, &h->ps, h->avctx);
if (ret < 0)
return ret;
// discard redundant pictures
if (sl->redundant_pic_count > 0)
return 0;
if (!h->setup_finished) {
if (sl->first_mb_addr == 0) { // FIXME better field boundary detection
// this slice starts a new field
// first decode any pending queued slices
if (h->nb_slice_ctx_queued) {
H264SliceContext tmp_ctx;
ret = ff_h264_execute_decode_slices(h);
if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
return ret;
memcpy(&tmp_ctx, h->slice_ctx, sizeof(tmp_ctx));
memcpy(h->slice_ctx, sl, sizeof(tmp_ctx));
memcpy(sl, &tmp_ctx, sizeof(tmp_ctx));
sl = h->slice_ctx;
}
if (h->current_slice && h->cur_pic_ptr && FIELD_PICTURE(h)) {
ff_h264_field_end(h, sl, 1);
}
h->current_slice = 0;
if (!h->first_field) {
if (h->cur_pic_ptr && !h->droppable) {
ff_thread_report_progress(&h->cur_pic_ptr->tf, INT_MAX,
h->picture_structure == PICT_BOTTOM_FIELD);
}
h->cur_pic_ptr = NULL;
}
}
if (h->current_slice == 0) {
ret = h264_field_start(h, sl, nal);
if (ret < 0)
return ret;
}
}
ret = h264_slice_init(h, sl, nal);
if (ret < 0)
return ret;
if ((h->avctx->skip_frame < AVDISCARD_NONREF || nal->ref_idc) &&
(h->avctx->skip_frame < AVDISCARD_BIDIR ||
sl->slice_type_nos != AV_PICTURE_TYPE_B) &&
(h->avctx->skip_frame < AVDISCARD_NONKEY ||
h->cur_pic_ptr->f->key_frame) &&
h->avctx->skip_frame < AVDISCARD_ALL) {
h->nb_slice_ctx_queued++;
}
return 0;
}
int ff_h264_get_slice_type(const H264SliceContext *sl)
{
switch (sl->slice_type) {
@ -2452,25 +2484,26 @@ finish:
* Call decode_slice() for each context.
*
* @param h h264 master context
* @param context_count number of contexts to execute
*/
int ff_h264_execute_decode_slices(H264Context *h, unsigned context_count)
int ff_h264_execute_decode_slices(H264Context *h)
{
AVCodecContext *const avctx = h->avctx;
H264SliceContext *sl;
int context_count = h->nb_slice_ctx_queued;
int ret = 0;
int i, j;
if (h->avctx->hwaccel)
if (h->avctx->hwaccel || context_count < 1)
return 0;
if (context_count == 1) {
int ret;
h->slice_ctx[0].next_slice_idx = h->mb_width * h->mb_height;
h->postpone_filter = 0;
ret = decode_slice(avctx, &h->slice_ctx[0]);
h->mb_y = h->slice_ctx[0].mb_y;
return ret;
if (ret < 0)
goto finish;
} else {
for (i = 0; i < context_count; i++) {
int next_slice_idx = h->mb_width * h->mb_height;
@ -2520,5 +2553,7 @@ int ff_h264_execute_decode_slices(H264Context *h, unsigned context_count)
}
}
return 0;
finish:
h->nb_slice_ctx_queued = 0;
return ret;
}

47
libavcodec/h264dec.c
View File

@ -508,7 +508,6 @@ static int get_last_needed_nal(H264Context *h)
static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
{
AVCodecContext *const avctx = h->avctx;
unsigned context_count = 0;
int nals_needed = 0; ///< number of NALs that need decoding before the next frame thread starts
int i, ret = 0;
@ -532,8 +531,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
for (i = 0; i < h->pkt.nb_nals; i++) {
H2645NAL *nal = &h->pkt.nals[i];
H264SliceContext *sl = &h->slice_ctx[context_count];
int err;
int max_slice_ctx, err;
if (avctx->skip_frame >= AVDISCARD_NONREF &&
nal->ref_idc == 0 && nal->type != H264_NAL_SEI)
@ -548,12 +546,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
case H264_NAL_IDR_SLICE:
idr(h); // FIXME ensure we don't lose some frames if there is reordering
case H264_NAL_SLICE:
sl->gb = nal->gb;
if ((err = ff_h264_decode_slice_header(h, sl, nal)))
break;
if (sl->redundant_pic_count > 0)
if ((err = ff_h264_queue_decode_slice(h, nal)))
break;
if (avctx->active_thread_type & FF_THREAD_FRAME && !h->avctx->hwaccel &&
@ -562,18 +555,14 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
h->setup_finished = 1;
}
if ((avctx->skip_frame < AVDISCARD_NONREF || nal->ref_idc) &&
(avctx->skip_frame < AVDISCARD_BIDIR ||
sl->slice_type_nos != AV_PICTURE_TYPE_B) &&
(avctx->skip_frame < AVDISCARD_NONKEY ||
h->cur_pic_ptr->f->key_frame) &&
avctx->skip_frame < AVDISCARD_ALL) {
if (avctx->hwaccel) {
max_slice_ctx = avctx->hwaccel ? 1 : h->nb_slice_ctx;
if (h->nb_slice_ctx_queued == max_slice_ctx) {
if (avctx->hwaccel)
ret = avctx->hwaccel->decode_slice(avctx, nal->raw_data, nal->raw_size);
if (ret < 0)
return ret;
} else
context_count++;
else
ret = ff_h264_execute_decode_slices(h);
if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
goto end;
}
break;
case H264_NAL_DPA:
@ -611,23 +600,14 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
nal->type, nal->size_bits);
}
if (context_count == h->nb_slice_ctx) {
ret = ff_h264_execute_decode_slices(h, context_count);
if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
goto end;
context_count = 0;
}
if (err < 0) {
av_log(h->avctx, AV_LOG_ERROR, "decode_slice_header error\n");
sl->ref_count[0] = sl->ref_count[1] = sl->list_count = 0;
}
}
if (context_count) {
ret = ff_h264_execute_decode_slices(h, context_count);
if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
goto end;
}
ret = ff_h264_execute_decode_slices(h);
if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
goto end;
ret = 0;
end:
@ -687,6 +667,7 @@ static int h264_decode_frame(AVCodecContext *avctx, void *data,
h->flags = avctx->flags;
h->setup_finished = 0;
h->nb_slice_ctx_queued = 0;
/* end of stream, output what is still in the buffers */
out:

12
libavcodec/h264dec.h
View File

@ -345,6 +345,7 @@ typedef struct H264Context {
H264SliceContext *slice_ctx;
int nb_slice_ctx;
int nb_slice_ctx_queued;
H2645Packet pkt;
@ -793,9 +794,14 @@ int ff_h264_slice_context_init(H264Context *h, H264SliceContext *sl);
void ff_h264_draw_horiz_band(const H264Context *h, H264SliceContext *sl, int y, int height);
int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl,
const H2645NAL *nal);
int ff_h264_execute_decode_slices(H264Context *h, unsigned context_count);
/**
* Submit a slice for decoding.
*
* Parse the slice header, starting a new field/frame if necessary. If any
* slices are queued for the previous field, they are decoded.
*/
int ff_h264_queue_decode_slice(H264Context *h, const H2645NAL *nal);
int ff_h264_execute_decode_slices(H264Context *h);
int ff_h264_update_thread_context(AVCodecContext *dst,
const AVCodecContext *src);