lavc: factor decoder validation/setup from avcodec_open2()

1 files changed, 41 insertions, 0 deletions

diff --git a/libavcodec/decode.c b/libavcodec/decode.c
index 5f7e9bda3e..c8e9be3a13 100644
--- a/libavcodec/decode.c
+++ b/libavcodec/decode.c
@@ -2004,3 +2004,44 @@ int ff_reget_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
     return ret;
 }
+
+int ff_decode_preinit(AVCodecContext *avctx)
+{
+    /* if the decoder init function was already called previously,
+     * free the already allocated subtitle_header before overwriting it */
+    av_freep(&avctx->subtitle_header);
+
+#if FF_API_THREAD_SAFE_CALLBACKS
+FF_DISABLE_DEPRECATION_WARNINGS
+    if ((avctx->thread_type & FF_THREAD_FRAME) &&
+        avctx->get_buffer2 != avcodec_default_get_buffer2 &&
+        !avctx->thread_safe_callbacks) {
+        av_log(avctx, AV_LOG_WARNING, "Requested frame threading with a "
+               "custom get_buffer2() implementation which is not marked as "
+               "thread safe. This is not supported anymore, make your "
+               "callback thread-safe.\n");
+    }
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
+
+    if (avctx->codec->max_lowres < avctx->lowres || avctx->lowres < 0) {
+        av_log(avctx, AV_LOG_WARNING, "The maximum value for lowres supported by the decoder is %d\n",
+               avctx->codec->max_lowres);
+        avctx->lowres = avctx->codec->max_lowres;
+    }
+
+    avctx->pts_correction_num_faulty_pts =
+    avctx->pts_correction_num_faulty_dts = 0;
+    avctx->pts_correction_last_pts =
+    avctx->pts_correction_last_dts = INT64_MIN;
+
+    if (   !CONFIG_GRAY && avctx->flags & AV_CODEC_FLAG_GRAY
+        && avctx->codec_descriptor->type == AVMEDIA_TYPE_VIDEO)
+        av_log(avctx, AV_LOG_WARNING,
+               "gray decoding requested but not enabled at configuration time\n");
+    if (avctx->flags2 & AV_CODEC_FLAG2_EXPORT_MVS) {
+        avctx->export_side_data |= AV_CODEC_EXPORT_DATA_MVS;
+    }
+
+    return 0;
+}