decode: restructure the core decoding code

Currently, the new decoding API is pretty much just a wrapper around the
old deprecated one. This is problematic, since it interferes with making
full use of the flexibility added by the new API. The old API should
also be removed at some future point.

Reorganize the code so that the new send_packet/receive_frame functions
call the actual decoding directly and change the old deprecated
avcodec_decode_* functions into wrappers around the new API.

The new internal API for decoders is now changing as well. Before this
commit, it mirrors the public API, so the decoders need to implement
send_packet() and receive_frame() callbacks. This turns out to require
awkward constructs in both the decoders and the generic code. After this
commit, the decoders only implement the receive_frame() callback and
call a new internal function, ff_decode_get_packet() to obtain input
data, in the same manner to how the bitstream filters now work.

avcodec will now always make a reference to the input packet, which means
that non-refcounted input packets will be copied. Keeping the previous
behaviour, where this copy could sometimes be avoided, would make the
code significantly more complex and fragile for only dubious gains,
since packets are typically small and everyone who cares about
performance should use refcounted packets anyway.

1 files changed, 21 insertions, 1 deletions

diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index b569b48f7a..8a422d7669 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -100,7 +100,7 @@ int av_codec_is_encoder(const AVCodec *codec)
 
 int av_codec_is_decoder(const AVCodec *codec)
 {
-    return codec && (codec->decode || codec->send_packet);
+    return codec && (codec->decode || codec->receive_frame);
 }
 
 av_cold void avcodec_register(AVCodec *codec)
@@ -421,6 +421,12 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
         goto free_and_end;
     }
 
+    avctx->internal->compat_decode_frame = av_frame_alloc();
+    if (!avctx->internal->compat_decode_frame) {
+        ret = AVERROR(ENOMEM);
+        goto free_and_end;
+    }
+
     avctx->internal->buffer_frame = av_frame_alloc();
     if (!avctx->internal->buffer_frame) {
         ret = AVERROR(ENOMEM);
@@ -433,6 +439,12 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
         goto free_and_end;
     }
 
+    avctx->internal->ds.in_pkt = av_packet_alloc();
+    if (!avctx->internal->ds.in_pkt) {
+        ret = AVERROR(ENOMEM);
+        goto free_and_end;
+    }
+
     avctx->internal->last_pkt_props = av_packet_alloc();
     if (!avctx->internal->last_pkt_props) {
         ret = AVERROR(ENOMEM);
@@ -717,9 +729,13 @@ FF_ENABLE_DEPRECATION_WARNINGS
     av_freep(&avctx->priv_data);
     if (avctx->internal) {
         av_frame_free(&avctx->internal->to_free);
+        av_frame_free(&avctx->internal->compat_decode_frame);
         av_frame_free(&avctx->internal->buffer_frame);
         av_packet_free(&avctx->internal->buffer_pkt);
         av_packet_free(&avctx->internal->last_pkt_props);
+
+        av_packet_free(&avctx->internal->ds.in_pkt);
+
         av_freep(&avctx->internal->pool);
     }
     av_freep(&avctx->internal);
@@ -758,9 +774,13 @@ av_cold int avcodec_close(AVCodecContext *avctx)
         if (avctx->codec && avctx->codec->close)
             avctx->codec->close(avctx);
         av_frame_free(&avctx->internal->to_free);
+        av_frame_free(&avctx->internal->compat_decode_frame);
         av_frame_free(&avctx->internal->buffer_frame);
         av_packet_free(&avctx->internal->buffer_pkt);
         av_packet_free(&avctx->internal->last_pkt_props);
+
+        av_packet_free(&avctx->internal->ds.in_pkt);
+
         for (i = 0; i < FF_ARRAY_ELEMS(pool->pools); i++)
             av_buffer_pool_uninit(&pool->pools[i]);
         av_freep(&avctx->internal->pool);