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AnimEncoder API: Use timestamp instead of duration as input to Add().

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When converting from video sources, the duration of current frame
is often unavailable until the next frame. So, we internally convert
timestamps to durations.

Change-Id: I20ad86361c22e014be7eb91f00d5d40108281351
This commit is contained in:
Urvang Joshi
2015-04-14 11:51:47 -07:00
parent 9904e365a8
commit d484555024
3 changed files with 110 additions and 33 deletions
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17
examples/gif2webp.c
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@ -91,7 +91,8 @@ int main(int argc, const char *argv[]) {
const char *in_file = NULL, *out_file = NULL;
FILE* out = NULL;
GifFileType* gif = NULL;
int duration = 0;
int frame_duration = 0;
int frame_timestamp = 0;
GIFDisposeMethod orig_dispose = GIF_DISPOSE_NONE;
WebPPicture frame; // Frame rectangle only (not disposed).
@ -330,7 +331,7 @@ int main(int argc, const char *argv[]) {
// Note that 'curr_canvas' is same as 'prev_canvas' at this point.
GIFBlendFrames(&frame, &gif_rect, &curr_canvas);
if (!WebPAnimEncoderAdd(enc, &curr_canvas, duration, &config)) {
if (!WebPAnimEncoderAdd(enc, &curr_canvas, frame_timestamp, &config)) {
fprintf(stderr, "Error! Cannot encode frame as WebP\n");
fprintf(stderr, "Error code: %d\n", curr_canvas.error_code);
}
@ -340,11 +341,14 @@ int main(int argc, const char *argv[]) {
GIFDisposeFrame(orig_dispose, &gif_rect, &prev_canvas, &curr_canvas);
GIFCopyPixels(&curr_canvas, &prev_canvas);
// Update timestamp (for next frame).
frame_timestamp += frame_duration;
// In GIF, graphic control extensions are optional for a frame, so we
// may not get one before reading the next frame. To handle this case,
// we reset frame properties to reasonable defaults for the next frame.
orig_dispose = GIF_DISPOSE_NONE;
duration = 0;
frame_duration = 0;
transparent_index = GIF_INDEX_INVALID;
break;
}
@ -359,7 +363,7 @@ int main(int argc, const char *argv[]) {
break; // Do nothing for now.
}
case GRAPHICS_EXT_FUNC_CODE: {
if (!GIFReadGraphicsExtension(data, &duration, &orig_dispose,
if (!GIFReadGraphicsExtension(data, &frame_duration, &orig_dispose,
&transparent_index)) {
goto End;
}
@ -424,6 +428,11 @@ int main(int argc, const char *argv[]) {
}
} while (!done);
// Last NULL frame.
if (!WebPAnimEncoderAdd(enc, NULL, frame_timestamp, NULL)) {
fprintf(stderr, "Error flushing WebP muxer.\n");
}
if (!WebPAnimEncoderAssemble(enc, &webp_data)) {
// TODO(urvang): Print actual error code.
fprintf(stderr, "ERROR assembling the WebP file.\n");