WebP encoder: use WebPAnimEncoder API when available.

WebPAnimEncoder API is a combination of encoder (WebPEncoder) and muxer
(WebPMux). It performs several optimizations to make it more efficient
than the combination of WebPEncode() and native ffmpeg muxer.

When WebPAnimEncoder API is used:
- In the encoder layer: we use WebPAnimEncoderAdd() instead of
  WebPEncode().
- The muxer layer: works like a raw muxer.

On the other hand, when WebPAnimEncoder API isn't available, the old code is
used as it is:
- In the codec layer: WebPEncode is used to encode each frame
- In the muxer layer:  ffmpeg muxer is used

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 146 insertions, 0 deletions

diff --git a/libavcodec/libwebpenc_animencoder.c b/libavcodec/libwebpenc_animencoder.c
new file mode 100644
index 0000000000..860973e7a3
--- /dev/null
+++ b/libavcodec/libwebpenc_animencoder.c
@@ -0,0 +1,146 @@
+/*
+ * WebP encoding support via libwebp
+ * Copyright (c) 2015 Urvang Joshi
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * WebP encoder using libwebp (WebPAnimEncoder API)
+ */
+
+#include "config.h"
+#include "libwebpenc_common.h"
+
+#if HAVE_WEBP_MUX_H
+#include <webp/mux.h>
+#endif
+
+typedef struct LibWebPAnimContext {
+    LibWebPContextCommon cc;
+    WebPAnimEncoder *enc;     // the main AnimEncoder object
+    int64_t prev_frame_pts;   // pts of the previously encoded frame.
+    int done;                 // If true, we have assembled the bitstream already
+} LibWebPAnimContext;
+
+static av_cold int libwebp_anim_encode_init(AVCodecContext *avctx)
+{
+    int ret = ff_libwebp_encode_init_common(avctx);
+    if (!ret) {
+        LibWebPAnimContext *s = avctx->priv_data;
+        WebPAnimEncoderOptions enc_options;
+        WebPAnimEncoderOptionsInit(&enc_options);
+        // TODO(urvang): Expose some options on command-line perhaps.
+        s->enc = WebPAnimEncoderNew(avctx->width, avctx->height, &enc_options);
+        if (!s->enc)
+            return AVERROR(EINVAL);
+        s->prev_frame_pts = -1;
+        s->done = 0;
+    }
+    return ret;
+}
+
+static int libwebp_anim_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
+                                     const AVFrame *frame, int *got_packet) {
+    LibWebPAnimContext *s = avctx->priv_data;
+    int ret;
+
+    if (!frame) {
+        if (s->done) {  // Second flush: return empty package to denote finish.
+            *got_packet = 0;
+            return 0;
+        } else {  // First flush: assemble bitstream and return it.
+            WebPData assembled_data = { 0 };
+            ret = WebPAnimEncoderAssemble(s->enc, &assembled_data);
+            if (ret) {
+                ret = ff_alloc_packet(pkt, assembled_data.size);
+                if (ret < 0)
+                    return ret;
+                memcpy(pkt->data, assembled_data.bytes, assembled_data.size);
+                s->done = 1;
+                pkt->flags |= AV_PKT_FLAG_KEY;
+                pkt->pts = pkt->dts = s->prev_frame_pts + 1;
+                *got_packet = 1;
+                return 0;
+            } else {
+                av_log(s, AV_LOG_ERROR,
+                       "WebPAnimEncoderAssemble() failed with error: %d\n",
+                       VP8_ENC_ERROR_OUT_OF_MEMORY);
+                return AVERROR(ENOMEM);
+            }
+        }
+    } else {
+        int timestamp_ms;
+        WebPPicture *pic = NULL;
+        AVFrame *alt_frame = NULL;
+        ret = ff_libwebp_get_frame(avctx, &s->cc, frame, &alt_frame, &pic);
+        if (ret < 0)
+            goto end;
+
+        timestamp_ms =
+            avctx->time_base.num * frame->pts * 1000 / avctx->time_base.den;
+        ret = WebPAnimEncoderAdd(s->enc, pic, timestamp_ms, &s->cc.config);
+        if (!ret) {
+                av_log(avctx, AV_LOG_ERROR,
+                       "Encoding WebP frame failed with error: %d\n",
+                   pic->error_code);
+            ret = ff_libwebp_error_to_averror(pic->error_code);
+            goto end;
+        }
+
+        pkt->pts = pkt->dts = frame->pts;
+        s->prev_frame_pts = frame->pts;  // Save for next frame.
+        ret = 0;
+        *got_packet = 1;
+
+end:
+        WebPPictureFree(pic);
+        av_freep(&pic);
+        av_frame_free(&alt_frame);
+        return ret;
+    }
+}
+
+static int libwebp_anim_encode_close(AVCodecContext *avctx)
+{
+    int ret = ff_libwebp_encode_close_common(avctx);
+    if (!ret) {
+        LibWebPAnimContext *s = avctx->priv_data;
+        WebPAnimEncoderDelete(s->enc);
+    }
+    return ret;
+}
+
+AVCodec ff_libwebp_anim_encoder = {
+    .name           = "libwebp_anim",
+    .long_name      = NULL_IF_CONFIG_SMALL("libwebp WebP image"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_WEBP,
+    .priv_data_size = sizeof(LibWebPAnimContext),
+    .init           = libwebp_anim_encode_init,
+    .encode2        = libwebp_anim_encode_frame,
+    .close          = libwebp_anim_encode_close,
+    .capabilities   = CODEC_CAP_DELAY,
+    .pix_fmts       = (const enum AVPixelFormat[]) {
+        AV_PIX_FMT_RGB32,
+        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUVA420P,
+        AV_PIX_FMT_NONE
+    },
+    .priv_class     = &class,
+    .defaults       = libwebp_defaults,
+};