On 23 February 2015 at 22:10, Alexander E. Patrakov <patrakov at gmail.com> wrote: > 23.02.2015 21:12, Peter Meerwald wrote: >> >> Hi Alexander, >> >>> Same bug as in module-loopback, pointed out by Georg Chini in a private >>> email. >> >> >> can you please elaborate? I fail to see the obviousness > > > The recv_counter == send_counter case looks like a neutral case here > (although I might be wrong), with no inherent discontinuity at this point. > So, any branch of the "if" should give the same result in this corner case, > and the whole point of the "if"/"PA_CLIP_SUB" construction, as I see it, is > to avoid producing negative numbers by mistake. > > The true branch simplifies to: buffer_latency += 0 > > The original false branch simplifies to: buffer_latency += > PA_CLIP_SUB(buffer_latency, 0), which, for buffer_latency > 0, means > buffer_latency += buffer_latency - 0. I.e. doubling the latency (as opposed > to not changing it), which looks strange even by itself. The falce branch would only be called when recv_counter > send_counter, so you'd never actually have the zero case. AIUI, this all just accounting for any "in-flight" rewinds being propagated from the sink-input to the source-output. Also, overwriting the value as you do loses the latency values that were added in previous lines. -- Arun
