enc.go:178:35: unnecessary conversion (unconvert)
if err := enc.bw.WriteBits(uint64(si.NSamples), 36); err != nil {
^
enc.go:543:34: unnecessary conversion (unconvert)
if _, err := enc.bw.Write([]byte(pic.Data)); err != nil {
^
frame/frame.go:161:17: Error return value of `md5sum.Write` is not checked (errcheck)
md5sum.Write(buf[:1])
^
frame/frame.go:165:17: Error return value of `md5sum.Write` is not checked (errcheck)
md5sum.Write(buf[:2])
^
frame/frame.go:170:17: Error return value of `md5sum.Write` is not checked (errcheck)
md5sum.Write(buf[:])
^
Updates #25.
