mpegenc: use avctx->slices as number of slices

Adds a new member to MpegEncContext to hold the number of used slice
contexts. Fixes segfaults with '-threads 17 -thread_type slice' and
fate-vsynth{1,2}-mpeg{2,4}thread{,_ilace} with --disable-pthreads.

1 files changed, 4 insertions, 5 deletions

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 2bde0fec2a..316a57d75e 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -1280,7 +1280,6 @@ int ff_h264_frame_start(H264Context *h){
     MpegEncContext * const s = &h->s;
     int i;
     const int pixel_shift = h->pixel_shift;
-    int thread_count = (s->avctx->active_thread_type & FF_THREAD_SLICE) ? s->avctx->thread_count : 1;
 
     if(MPV_frame_start(s, s->avctx) < 0)
         return -1;
@@ -1309,7 +1308,7 @@ int ff_h264_frame_start(H264Context *h){
 
     /* can't be in alloc_tables because linesize isn't known there.
      * FIXME: redo bipred weight to not require extra buffer? */
-    for(i = 0; i < thread_count; i++)
+    for(i = 0; i < s->slice_context_count; i++)
         if(h->thread_context[i] && !h->thread_context[i]->s.obmc_scratchpad)
             h->thread_context[i]->s.obmc_scratchpad = av_malloc(16*6*s->linesize);
 
@@ -2826,7 +2825,7 @@ static int decode_slice_header(H264Context *h, H264Context *h0){
                 return -1;
             }
         } else {
-            for(i = 1; i < s->avctx->thread_count; i++) {
+            for(i = 1; i < s->slice_context_count; i++) {
                 H264Context *c;
                 c = h->thread_context[i] = av_malloc(sizeof(H264Context));
                 memcpy(c, h->s.thread_context[i], sizeof(MpegEncContext));
@@ -2839,7 +2838,7 @@ static int decode_slice_header(H264Context *h, H264Context *h0){
                 clone_tables(c, h, i);
             }
 
-            for(i = 0; i < s->avctx->thread_count; i++)
+            for(i = 0; i < s->slice_context_count; i++)
                 if (context_init(h->thread_context[i]) < 0) {
                     av_log(h->s.avctx, AV_LOG_ERROR, "context_init() failed.\n");
                     return -1;
@@ -3742,7 +3741,7 @@ 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 nal_index;
 
-    h->max_contexts = (HAVE_THREADS && (s->avctx->active_thread_type&FF_THREAD_SLICE)) ? avctx->thread_count : 1;
+    h->max_contexts = s->slice_context_count;
     if(!(s->flags2 & CODEC_FLAG2_CHUNKS)){
         h->current_slice = 0;
         if (!s->first_field)