vpxdec: Relocate WebM input support.

- Move it to webmdec.c and webmdec.h.
- Also, tidy up obvious style nits in the vicinity of code I was
  already touching.

Change-Id: Ie2898d06e73c1e9030d9c8d465b73ee7edc3c02a

webmdec.c

diff --git a/webmdec.c b/webmdec.c
new file mode 100644
index 0000000..4bf7c7e
--- /dev/null
+++ b/webmdec.c
@@ -0,0 +1,193 @@
+/*
+ *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "./webmdec.h"
+
+#include <stdarg.h>
+
+#include "nestegg/include/nestegg/nestegg.h"
+
+static int nestegg_read_cb(void *buffer, size_t length, void *userdata) {
+  FILE *f = userdata;
+
+  if (fread(buffer, 1, length, f) < length) {
+    if (ferror(f))
+      return -1;
+    if (feof(f))
+      return 0;
+  }
+  return 1;
+}
+
+static int nestegg_seek_cb(int64_t offset, int whence, void *userdata) {
+  switch (whence) {
+    case NESTEGG_SEEK_SET:
+      whence = SEEK_SET;
+      break;
+    case NESTEGG_SEEK_CUR:
+      whence = SEEK_CUR;
+      break;
+    case NESTEGG_SEEK_END:
+      whence = SEEK_END;
+      break;
+  };
+  return fseek(userdata, (int32_t)offset, whence) ? -1 : 0;
+}
+
+static int64_t nestegg_tell_cb(void *userdata) {
+  return ftell(userdata);
+}
+
+static void nestegg_log_cb(nestegg *context,
+                           unsigned int severity,
+                           char const *format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  vfprintf(stderr, format, ap);
+  fprintf(stderr, "\n");
+  va_end(ap);
+}
+
+int file_is_webm(struct WebmInputContext *webm_ctx,
+                 struct VpxInputContext *vpx_ctx) {
+  uint32_t i, n;
+  int track_type = -1;
+  int codec_id;
+
+  nestegg_io io = {nestegg_read_cb, nestegg_seek_cb, nestegg_tell_cb, 0};
+  nestegg_video_params params;
+
+  io.userdata = vpx_ctx->file;
+  if (nestegg_init(&webm_ctx->nestegg_ctx, io, NULL))
+    goto fail;
+
+  if (nestegg_track_count(webm_ctx->nestegg_ctx, &n))
+    goto fail;
+
+  for (i = 0; i < n; i++) {
+    track_type = nestegg_track_type(webm_ctx->nestegg_ctx, i);
+
+    if (track_type == NESTEGG_TRACK_VIDEO)
+      break;
+    else if (track_type < 0)
+      goto fail;
+  }
+
+  codec_id = nestegg_track_codec_id(webm_ctx->nestegg_ctx, i);
+  if (codec_id == NESTEGG_CODEC_VP8) {
+    vpx_ctx->fourcc = VP8_FOURCC_MASK;
+  } else if (codec_id == NESTEGG_CODEC_VP9) {
+    vpx_ctx->fourcc = VP9_FOURCC_MASK;
+  } else {
+    fatal("Not VPx video, quitting.\n");
+  }
+
+  webm_ctx->video_track = i;
+
+  if (nestegg_track_video_params(webm_ctx->nestegg_ctx, i, &params))
+    goto fail;
+
+  vpx_ctx->framerate.denominator = 0;
+  vpx_ctx->framerate.numerator = 0;
+  vpx_ctx->width = params.width;
+  vpx_ctx->height = params.height;
+
+  return 1;
+
+ fail:
+  webm_ctx->nestegg_ctx = NULL;
+  rewind(vpx_ctx->file);
+
+  return 0;
+}
+
+int webm_read_frame(struct WebmInputContext *webm_ctx,
+                    uint8_t **buffer,
+                    size_t *bytes_in_buffer,
+                    size_t *buffer_size) {
+  if (webm_ctx->chunk >= webm_ctx->chunks) {
+    uint32_t track;
+
+    do {
+      /* End of this packet, get another. */
+      if (webm_ctx->pkt)
+        nestegg_free_packet(webm_ctx->pkt);
+
+      if (nestegg_read_packet(webm_ctx->nestegg_ctx, &webm_ctx->pkt) <= 0 ||
+          nestegg_packet_track(webm_ctx->pkt, &track)) {
+        return 1;
+      }
+    } while (track != webm_ctx->video_track);
+
+    if (nestegg_packet_count(webm_ctx->pkt, &webm_ctx->chunks))
+      return 1;
+
+    webm_ctx->chunk = 0;
+  }
+
+  if (nestegg_packet_data(webm_ctx->pkt, webm_ctx->chunk,
+                          buffer, bytes_in_buffer)) {
+    return 1;
+  }
+
+  webm_ctx->chunk++;
+  return 0;
+}
+
+int webm_guess_framerate(struct WebmInputContext *webm_ctx,
+                         struct VpxInputContext *vpx_ctx) {
+  uint32_t i;
+  uint64_t tstamp = 0;
+
+  /* Check to see if we can seek before we parse any data. */
+  if (nestegg_track_seek(webm_ctx->nestegg_ctx, webm_ctx->video_track, 0)) {
+    warn("Failed to guess framerate (no Cues), set to 30fps.\n");
+    vpx_ctx->framerate.numerator = 30;
+    vpx_ctx->framerate.denominator  = 1;
+    return 0;
+  }
+
+  /* Guess the framerate. Read up to 1 second, or 50 video packets,
+   * whichever comes first.
+   */
+  for (i = 0; tstamp < 1000000000 && i < 50;) {
+    nestegg_packet *pkt;
+    uint32_t track;
+
+    if (nestegg_read_packet(webm_ctx->nestegg_ctx, &pkt) <= 0)
+      break;
+
+    nestegg_packet_track(pkt, &track);
+    if (track == webm_ctx->video_track) {
+      nestegg_packet_tstamp(pkt, &tstamp);
+      ++i;
+    }
+
+    nestegg_free_packet(pkt);
+  }
+
+  if (nestegg_track_seek(webm_ctx->nestegg_ctx, webm_ctx->video_track, 0))
+    goto fail;
+
+  vpx_ctx->framerate.numerator = (i - 1) * 1000000;
+  vpx_ctx->framerate.denominator = (int)(tstamp / 1000);
+  return 0;
+
+ fail:
+  nestegg_destroy(webm_ctx->nestegg_ctx);
+  webm_ctx->nestegg_ctx = NULL;
+  rewind(vpx_ctx->file);
+  return 1;
+}
+
+void webm_free(struct WebmInputContext *webm_ctx) {
+  if (webm_ctx && webm_ctx->nestegg_ctx)
+    nestegg_destroy(webm_ctx->nestegg_ctx);
+}