On Thu, Jun 9, 2016 at 4:29 AM, Anton Khirnov <an...@khirnov.net> wrote:
> There is no bitstream parsing in that block and messing with
> decoder-global state is not something that belongs into header parsing.
>
> Nothing else in this function depends on the value of current_slice,
> except for two validity checks. Those checks are also moved out of
> slice_header_parse().
> ---
> libavcodec/h264_slice.c | 68
> ++++++++++++++++++++++++-------------------------
> 1 file changed, 33 insertions(+), 35 deletions(-)
>
> diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
> index 17608b4..c43a0be 100644
> --- a/libavcodec/h264_slice.c
> +++ b/libavcodec/h264_slice.c
> @@ -1177,21 +1177,6 @@ static int h264_slice_header_parse(H264Context *h,
> H264SliceContext *sl,
>
> sl->first_mb_addr = get_ue_golomb(&sl->gb);
>
> - 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;
> - }
> - }
> -
> slice_type = get_ue_golomb_31(&sl->gb);
> if (slice_type > 9) {
> av_log(h->avctx, AV_LOG_ERROR,
> @@ -1226,11 +1211,6 @@ static int h264_slice_header_parse(H264Context *h,
> H264SliceContext *sl,
> sl->pps_id);
> return AVERROR_INVALIDDATA;
> }
> - if (h->current_slice > 0 &&
> - 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");
> - return AVERROR_INVALIDDATA;
> - }
> pps = (const PPS*)h->ps.pps_list[sl->pps_id]->data;
>
> if (!h->ps.sps_list[pps->sps_id]) {
> @@ -1265,21 +1245,6 @@ static int h264_slice_header_parse(H264Context *h,
> H264SliceContext *sl,
> sl->picture_structure = picture_structure;
> sl->mb_field_decoding_flag = picture_structure != PICT_FRAME;
>
> - if (h->current_slice != 0) {
> - if (h->picture_structure != picture_structure ||
> - h->droppable != droppable) {
> - av_log(h->avctx, AV_LOG_ERROR,
> - "Changing field mode (%d -> %d) between slices is not
> allowed\n",
> - h->picture_structure, picture_structure);
> - return AVERROR_INVALIDDATA;
> - } else if (!h->cur_pic_ptr) {
> - av_log(h->avctx, AV_LOG_ERROR,
> - "unset cur_pic_ptr on slice %d\n",
> - h->current_slice + 1);
> - return AVERROR_INVALIDDATA;
> - }
> - }
> -
> if (picture_structure == PICT_FRAME) {
> h->curr_pic_num = h->poc.frame_num;
> h->max_pic_num = 1 << sps->log2_max_frame_num;
> @@ -1430,10 +1395,43 @@ int ff_h264_decode_slice_header(H264Context *h,
> H264SliceContext *sl,
> if (ret < 0)
> return ret;
>
> + if (sl->first_mb_addr == 0) { // FIXME better field boundary detection
does this FIXME still apply?
> + 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;
> + } else {
> + 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");
> + return AVERROR_INVALIDDATA;
> + }
> +
> + if (h->picture_structure != sl->picture_structure ||
> + h->droppable != (nal->ref_idc == 0)) {
> + av_log(h->avctx, AV_LOG_ERROR,
> + "Changing field mode (%d -> %d) between slices is not
> allowed\n",
> + h->picture_structure, sl->picture_structure);
> + return AVERROR_INVALIDDATA;
> + } else if (!h->cur_pic_ptr) {
> + av_log(h->avctx, AV_LOG_ERROR,
> + "unset cur_pic_ptr on slice %d\n",
> + h->current_slice + 1);
> + return AVERROR_INVALIDDATA;
> + }
> }
>
> assert(h->mb_num == h->mb_width * h->mb_height);
> --
probably ok
--
Vittorio
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