theora: export cropping information instead of handling it internally

libavcodec/vp3.c

@@ -1983,6 +1983,7 @@ static int vp3_decode_frame(AVCodecContext *avctx,
                             void *data, int *got_frame,
                             AVPacket *avpkt)
 {
+    AVFrame     *frame  = data;
     const uint8_t *buf  = avpkt->data;
     int buf_size        = avpkt->size;
     Vp3DecodeContext *s = avctx->priv_data;
@@ -2122,12 +2123,12 @@ static int vp3_decode_frame(AVCodecContext *avctx,
     /* output frame, offset as needed */
     if ((ret = av_frame_ref(data, s->current_frame.f)) < 0)
         return ret;
-    for (i = 0; i < 3; i++) {
-        AVFrame *dst = data;
-        int off = (s->offset_x >> (i && s->chroma_y_shift)) +
-                  (s->offset_y >> (i && s->chroma_y_shift)) * dst->linesize[i];
-        dst->data[i] += off;
-    }
+
+    frame->crop_left   = s->offset_x;
+    frame->crop_right  = avctx->coded_width - avctx->width - s->offset_x;
+    frame->crop_top    = s->offset_y;
+    frame->crop_bottom = avctx->coded_height - avctx->height - s->offset_y;
+
     *got_frame = 1;
 
     if (!HAVE_THREADS || !(s->avctx->active_thread_type & FF_THREAD_FRAME)) {
@@ -2290,13 +2291,6 @@ static int theora_decode_header(AVCodecContext *avctx, GetBitContext *gb)
         // to normal axis ([0,0] upper left)
         s->offset_x = offset_x;
         s->offset_y = s->height - visible_height - offset_y;
-
-        if ((s->offset_x & 0x1F) && !(avctx->flags & AV_CODEC_FLAG_UNALIGNED)) {
-            s->offset_x &= ~0x1F;
-            av_log(avctx, AV_LOG_WARNING, "Reducing offset_x from %d to %d"
-                   "chroma samples to preserve alignment.\n",
-                   offset_x, s->offset_x);
-        }
     }
 
     if (colorspace == 1)
@@ -2499,7 +2493,8 @@ AVCodec ff_theora_decoder = {
                              AV_CODEC_CAP_FRAME_THREADS,
     .flush                 = vp3_decode_flush,
     .init_thread_copy      = ONLY_IF_THREADS_ENABLED(vp3_init_thread_copy),
-    .update_thread_context = ONLY_IF_THREADS_ENABLED(vp3_update_thread_context)
+    .update_thread_context = ONLY_IF_THREADS_ENABLED(vp3_update_thread_context),
+    .caps_internal         = FF_CODEC_CAP_EXPORTS_CROPPING,
 };
 #endif