h264: remove an artificial restriction on the number of slice threads

This limit is now unnecessary, we can easily support an arbitrary number
of threads.

libavcodec/h264.c

@@ -285,7 +285,6 @@ static int h264_init_context(AVCodecContext *avctx, H264Context *h)
     h->avctx                 = avctx;
 
     h->picture_structure     = PICT_FRAME;
-    h->slice_context_count   = 1;
     h->workaround_bugs       = avctx->workaround_bugs;
     h->flags                 = avctx->flags;
     h->poc.prev_poc_msb      = 1 << 16;
@@ -300,7 +299,7 @@ static int h264_init_context(AVCodecContext *avctx, H264Context *h)
 
     avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
 
-    h->nb_slice_ctx = (avctx->active_thread_type & FF_THREAD_SLICE) ?  H264_MAX_THREADS : 1;
+    h->nb_slice_ctx = (avctx->active_thread_type & FF_THREAD_SLICE) ? avctx->thread_count : 1;
     h->slice_ctx = av_mallocz_array(h->nb_slice_ctx, sizeof(*h->slice_ctx));
     if (!h->slice_ctx) {
         h->nb_slice_ctx = 0;
@@ -809,7 +808,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
     int nals_needed = 0; ///< number of NALs that need decoding before the next frame thread starts
     int i, ret = 0;
 
-    h->max_contexts = h->slice_context_count;
+    h->max_contexts = h->nb_slice_ctx;
     if (!(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS)) {
         h->current_slice = 0;
         if (!h->first_field)

libavcodec/h264.h

@@ -49,7 +49,6 @@
 #include "videodsp.h"
 
 #define H264_MAX_PICTURE_COUNT 32
-#define H264_MAX_THREADS       16
 
 #define MAX_SPS_COUNT          32
 #define MAX_PPS_COUNT         256
@@ -593,8 +592,6 @@ typedef struct H264Context {
      */
     int max_contexts;
 
-    int slice_context_count;
-
     /** @} */
 
     /**

libavcodec/h264_slice.c

@@ -829,9 +829,6 @@ static int init_dimensions(H264Context *h)
 static int h264_slice_header_init(H264Context *h)
 {
     const SPS *sps = h->ps.sps;
-    int nb_slices = (HAVE_THREADS &&
-                     h->avctx->active_thread_type & FF_THREAD_SLICE) ?
-                    h->avctx->thread_count : 1;
     int i, ret;
 
     ff_set_sar(h->avctx, sps->sar);
@@ -877,18 +874,6 @@ static int h264_slice_header_init(H264Context *h)
                       sps->chroma_format_idc);
     ff_videodsp_init(&h->vdsp, sps->bit_depth_luma);
 
-    if (nb_slices > H264_MAX_THREADS || (nb_slices > h->mb_height && h->mb_height)) {
-        int max_slices;
-        if (h->mb_height)
-            max_slices = FFMIN(H264_MAX_THREADS, h->mb_height);
-        else
-            max_slices = H264_MAX_THREADS;
-        av_log(h->avctx, AV_LOG_WARNING, "too many threads/slices %d,"
-               " reducing to %d\n", nb_slices, max_slices);
-        nb_slices = max_slices;
-    }
-    h->slice_context_count = nb_slices;
-
     if (!HAVE_THREADS || !(h->avctx->active_thread_type & FF_THREAD_SLICE)) {
         ret = ff_h264_slice_context_init(h, &h->slice_ctx[0]);
         if (ret < 0) {
@@ -896,7 +881,7 @@ static int h264_slice_header_init(H264Context *h)
             return ret;
         }
     } else {
-        for (i = 0; i < h->slice_context_count; i++) {
+        for (i = 0; i < h->nb_slice_ctx; i++) {
             H264SliceContext *sl = &h->slice_ctx[i];
 
             sl->h264               = h;