Re: [Discuss-gnuradio] Stream tags and None 1 to 1 processing blocks. Failure to propagate

[Colby Boyer]

Yea, sorry for vague email. Was tired and in a hurry. I encountered the error when dealing with a bank of polyphase resamplers. I traced the tag copying to

gnuradio-core/src/lib/runtime/gr_block_executor.cc line 121 for none 1 to 1 (fractional rate) blocks.

The logic written originally is pmt::pmt_from_uint64(newcount * rrate) where rrate is the block's rate and newcount is the absolute position of the tag on the input.

I run into this following situation. Say input sample to the resampler is tagged at index 800. With a resample rate of 0.9984 we get the product of 798.72. This will round down to 798. However the next block has already processed samples 0 to 798. It is now looking at 799 and forward. So the tag never propagates.

-Colby

On Tue, Jul 19, 2011 at 5:03 PM, Tom Rondeau <address@hidden> wrote:

On Mon, Jul 18, 2011 at 10:28 PM, Colby Boyer <address@hidden> wrote:

Hi All,

I have seem to run into an issue with the stream tags and interp/decimation processing blocks. When computing to add the tag to the proper output offset, it always rounds down. In certain cases, computed offset is X.YZ, where the first input item to the next block is at X+1. So the stream tag is *never* copied over.

One fix might be the ceil function?

--Colby

Eric and I went over this pretty carefully, and I thought we handled it correctly. I wasn't able to follow your XYZ logic in your email. Could you be more specific about what the problem is that you are seeing?

Tom