[FFmpeg-cvslog] h264: drop any pretense of support for data partitioning

[Anton Khirnov]

ffmpeg | branch: master | Anton Khirnov <anton at khirnov.net> | Mon Jan 19 21:58:12 2015 +0100| [167e004e1aca7765686ed95d7cd8ea5064d4f6f6] | committer: Anton Khirnov

h264: drop any pretense of support for data partitioning

It does not work correctly and apparently never did. There is no
indication that this (mis)feature is ever used in the wild or even that
any software other than the reference supports it.

Since the code that attempts to support it adds some nontrivial
complexity and has resulted in several bugs in the past, it is better to
just drop it.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=167e004e1aca7765686ed95d7cd8ea5064d4f6f6
---

 libavcodec/h264.c       |   45 +++------------------------------------------
 libavcodec/h264.h       |    1 -
 libavcodec/h264_slice.c |    1 -
 3 files changed, 3 insertions(+), 44 deletions(-)

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 2aea35e..be0dca4 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -1499,7 +1499,6 @@ again:
                 init_get_bits(&hx->gb, ptr, bit_length);
                 hx->intra_gb_ptr      =
                 hx->inter_gb_ptr      = &hx->gb;
-                hx->data_partitioning = 0;
 
                 if ((err = ff_h264_decode_slice_header(hx, h)))
                     break;
@@ -1552,46 +1551,11 @@ again:
                 }
                 break;
             case NAL_DPA:
-                if (h->avctx->flags & CODEC_FLAG2_CHUNKS) {
-                    av_log(h->avctx, AV_LOG_ERROR,
-                           "Decoding in chunks is not supported for "
-                           "partitioned slices.\n");
-                    return AVERROR(ENOSYS);
-                }
-
-                init_get_bits(&hx->gb, ptr, bit_length);
-                hx->intra_gb_ptr =
-                hx->inter_gb_ptr = NULL;
-
-                if ((err = ff_h264_decode_slice_header(hx, h)) < 0) {
-                    /* make sure data_partitioning is cleared if it was set
-                     * before, so we don't try decoding a slice without a valid
-                     * slice header later */
-                    h->data_partitioning = 0;
-                    break;
-                }
-
-                hx->data_partitioning = 1;
-                break;
             case NAL_DPB:
-                init_get_bits(&hx->intra_gb, ptr, bit_length);
-                hx->intra_gb_ptr = &hx->intra_gb;
-                break;
             case NAL_DPC:
-                init_get_bits(&hx->inter_gb, ptr, bit_length);
-                hx->inter_gb_ptr = &hx->inter_gb;
-
-                if (hx->redundant_pic_count == 0 &&
-                    hx->intra_gb_ptr &&
-                    hx->data_partitioning &&
-                    h->cur_pic_ptr && h->context_initialized &&
-                    (avctx->skip_frame < AVDISCARD_NONREF || hx->nal_ref_idc) &&
-                    (avctx->skip_frame < AVDISCARD_BIDIR  ||
-                     hx->slice_type_nos != AV_PICTURE_TYPE_B) &&
-                    (avctx->skip_frame < AVDISCARD_NONKEY ||
-                     hx->slice_type_nos == AV_PICTURE_TYPE_I) &&
-                    avctx->skip_frame < AVDISCARD_ALL)
-                    context_count++;
+                avpriv_request_sample(avctx, "data partitioning");
+                ret = AVERROR(ENOSYS);
+                goto end;
                 break;
             case NAL_SEI:
                 init_get_bits(&h->gb, ptr, bit_length);
@@ -1718,9 +1682,6 @@ static int h264_decode_frame(AVCodecContext *avctx, void *data,
     int ret;
 
     h->flags = avctx->flags;
-    /* reset data partitioning here, to ensure GetBitContexts from previous
-     * packets do not get used. */
-    h->data_partitioning = 0;
 
     /* end of stream, output what is still in the buffers */
 out:
diff --git a/libavcodec/h264.h b/libavcodec/h264.h
index ad36549..37e4cf4 100644
--- a/libavcodec/h264.h
+++ b/libavcodec/h264.h
@@ -324,7 +324,6 @@ typedef struct H264Context {
 
     int qscale;
     int droppable;
-    int data_partitioning;
     int coded_picture_number;
     int low_delay;
 
diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
index e291aab..4eb2767 100644
--- a/libavcodec/h264_slice.c
+++ b/libavcodec/h264_slice.c
@@ -1127,7 +1127,6 @@ static int h264_slice_header_init(H264Context *h, int reinit)
             c->chroma_y_shift    = h->chroma_y_shift;
             c->qscale            = h->qscale;
             c->droppable         = h->droppable;
-            c->data_partitioning = h->data_partitioning;
             c->low_delay         = h->low_delay;
             c->mb_width          = h->mb_width;
             c->mb_height         = h->mb_height;