[FFmpeg-devel] [PATCH v2] webp: implement FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM

[Alex Xu (Hello71)]

Roughly doubles webp performance for common applications (ffmpeg,
ffprobe, mpv) due to speeding up avformat_find_stream_info.

Lossy needs no patches since vp8.c already implements skip_frame.
Lossless needs hook to understand skip_frame. Also the "image data not
found" message is fixed, which was already broken with manual
-skip_frame but would now be exposed in default operation.
---
 libavcodec/webp.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/libavcodec/webp.c b/libavcodec/webp.c
index d5a81fd527..e425bce3ff 100644
--- a/libavcodec/webp.c
+++ b/libavcodec/webp.c
@@ -1126,6 +1126,9 @@ static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
         h = s->height;
     }
 
+    if (avctx->skip_frame == AVDISCARD_ALL)
+        return data_size;
+
     /* parse transformations */
     s->nb_transforms = 0;
     s->reduced_width = s->width;
@@ -1339,7 +1342,7 @@ static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     AVFrame * const p = data;
     WebPContext *s = avctx->priv_data;
     GetByteContext gb;
-    int ret;
+    int ret, got_frame_chunk = 0;
     uint32_t chunk_type, chunk_size;
     int vp8x_flags = 0;
 
@@ -1392,6 +1395,7 @@ static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                                              chunk_size);
                 if (ret < 0)
                     return ret;
+                got_frame_chunk = 1;
             }
             bytestream2_skip(&gb, chunk_size);
             break;
@@ -1403,6 +1407,7 @@ static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                 if (ret < 0)
                     return ret;
                 avctx->properties |= FF_CODEC_PROPERTY_LOSSLESS;
+                got_frame_chunk = 1;
             }
             bytestream2_skip(&gb, chunk_size);
             break;
@@ -1524,7 +1529,7 @@ exif_end:
         }
     }
 
-    if (!*got_frame) {
+    if (!got_frame_chunk) {
         av_log(avctx, AV_LOG_ERROR, "image data not found\n");
         return AVERROR_INVALIDDATA;
     }
@@ -1565,5 +1570,5 @@ const AVCodec ff_webp_decoder = {
     .decode         = webp_decode_frame,
     .close          = webp_decode_close,
     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
-    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM,
 };
-- 
2.34.1