On 4/10/2021 10:28 PM, Andreas Rheinhardt wrote:
James Almer:
On 4/10/2021 9:39 PM, Andreas Rheinhardt wrote:
They are essentially forbidden in our encoding API as they are
considered empty. So just set the data, but leave the size at zero.
This doesn't seem like a good solution. You're propagating dummy packets
when the encoder didn't produce any. It's an ugly hack to workaround a
misbehaving muxer.
As this is a AV_CODEC_CAP_DELAY encoder, you're supposed to set
got_packet to 0 in this scenario.
The muxer should then not expect this encoder to return more than one
packet, which is all it ever truly produces, to assume it effectively
came from it.
Then feel free to fix this yourself. All I know is that the muxer
explicitly checks for the number of frames to be > 1. Not that I know
why. (And I also presume the "Note: without the following, avio only
writes 8 bytes to the file" to be outdated.)
I assume the muxer expected more than one packet because that's what the
encoder produced, even if only the last one was legit. It nonetheless is
a weird check, since for the purpose of writing the loop value it makes
no difference whatsoever if the muxer got one or several packets, only
that the is_animated_webp_packet() check succeeded, and that won't
happen if a non animated webp image was fed.
(The old encoding API allowed such packets: It used buffer_pkt_valid
to record whether the packet is empty or not. This has been changed
in 827d6fe73d2f5472c1c2128eb14fab6a4db29032 which broke said encoder.
Said regression has been reported in #9179 which this commit partially
fixes.)
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
libavcodec/libwebpenc_animencoder.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/libavcodec/libwebpenc_animencoder.c
b/libavcodec/libwebpenc_animencoder.c
index 7f35a0b939..d871e85d43 100644
--- a/libavcodec/libwebpenc_animencoder.c
+++ b/libavcodec/libwebpenc_animencoder.c
@@ -34,6 +34,7 @@ typedef struct LibWebPAnimContext {
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
+ uint8_t padding_buf[AV_INPUT_BUFFER_PADDING_SIZE];
} LibWebPAnimContext;
static av_cold int libwebp_anim_encode_init(AVCodecContext *avctx)
@@ -103,6 +104,8 @@ static int
libwebp_anim_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
}
pkt->pts = pkt->dts = frame->pts;
+ // Packets without data and side-data are not supported by
the API
+ pkt->data = s->padding_buf;
s->prev_frame_pts = frame->pts; // Save for next frame.
ret = 0;
*got_packet = 1;
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