Speed up initialization of the avcodec decoder by calling avformat_find_stream_info only when required metadata is not present in the media file header (rare, i.e. mpeg-ts).
The avformat_find_stream_info function can perform a video frame decode, which offers increased accuracy at the expense of additional compute & latency. We will still call avformat_find_stream_info when metadata is not known, but it's not the common case.
Testing with a 14MB mp4 file that was previously causing performance issues showed a 675x speed-up (0.882 ms vs 592 ms):
Before
goos: linux
goarch: amd64
pkg: github.com/discord/lilliput
cpu: Intel(R) Xeon(R) CPU @ 3.10GHz
BenchmarkNewDecoder-16 2 596281993 ns/op 288 B/op 11 allocs/op
PASS
coverage: 7.1% of statements
ok github.com/discord/lilliput 1.816s
After
goos: linux
goarch: amd64
pkg: github.com/discord/lilliput
cpu: Intel(R) Xeon(R) CPU @ 3.10GHz
BenchmarkNewDecoder-16 1448 882478 ns/op 286 B/op 10 allocs/op
PASS
coverage: 7.1% of statements
ok github.com/discord/lilliput 1.446s
Speed up initialization of the avcodec decoder by calling
avformat_find_stream_infoonly when required metadata is not present in the media file header (rare, i.e. mpeg-ts).The
avformat_find_stream_infofunction can perform a video frame decode, which offers increased accuracy at the expense of additional compute & latency. We will still callavformat_find_stream_infowhen metadata is not known, but it's not the common case.Testing with a 14MB mp4 file that was previously causing performance issues showed a 675x speed-up (0.882 ms vs 592 ms):
Before
After