[Freeswitch-dev] switch_core_media_bug_add and some related questions
Hi all, I'm trying to make a legal intercept module. My first attempt was to get the raw RTP packets from switch_frame_t, but they don't seem to be available. My second attempt is to get the raw pcm data from the frames, which seems to work. I still have a few questions though: - On setting the mediabug (switch_core_media_bug_add), I can pass an enum. Is there a difference between SMBF_BOTH (0) or SMBF_READ_STREAM | SMBF_WRITE_STREAM (1+2=3) ? - In the callback function passed to the bug, what does each of the following switch_abc_type_t mean ? At first I assumed that READ and WRITE state the direction of the media, but some recording functions only use the READ so that can't be true. SWITCH_ABC_TYPE_INIT SWITCH_ABC_TYPE_READ_PING SWITCH_ABC_TYPE_CLOSE SWITCH_ABC_TYPE_READ SWITCH_ABC_TYPE_WRITE SWITCH_ABC_TYPE_READ_REPLACE SWITCH_ABC_TYPE_WRITE_REPLACE - When the callback function is called with SWITCH_ABC_TYPE_READ, I'm doing a switch_core_media_bug_read to copy all media to a switch_frame_t. To then get the raw data, I see in many examples that the size of the frame is retrieved by "(switch_size_t) frame.datalen / 2". Why the division by two ? - I thought that frame.data contained a un-encoded version of the RTP packet, but the datalen seems to differ when I'm calling in over g711 or g722. What format is frame.data ? Thanks a lot ! regards, Leon
READ_STREAM and WRITE_STREAM give you muxed stream of both directions at once by buffering it. READ_REPLACE and WRITE_REPLACE give you the packets as they happen in that particular direction with added capability that you can write new data into the frame to take it's place. The format in a media bug is always raw signed linear. datalen is the size in bytes of the decoded payload. g711 decodes to 320 bytes per 20ms packet g722 decodes to twice that, 640, since it's 16lhz audio. On Thu, Oct 1, 2009 at 4:45 AM, Leon de Rooij <leon@scarlet-internet.nl>wrote:
Hi all,
I'm trying to make a legal intercept module. My first attempt was to get the raw RTP packets from switch_frame_t, but they don't seem to be available. My second attempt is to get the raw pcm data from the frames, which seems to work. I still have a few questions though:
- On setting the mediabug (switch_core_media_bug_add), I can pass an enum. Is there a difference between SMBF_BOTH (0) or SMBF_READ_STREAM | SMBF_WRITE_STREAM (1+2=3) ?
- In the callback function passed to the bug, what does each of the following switch_abc_type_t mean ? At first I assumed that READ and WRITE state the direction of the media, but some recording functions only use the READ so that can't be true.
SWITCH_ABC_TYPE_INIT SWITCH_ABC_TYPE_READ_PING SWITCH_ABC_TYPE_CLOSE SWITCH_ABC_TYPE_READ SWITCH_ABC_TYPE_WRITE SWITCH_ABC_TYPE_READ_REPLACE SWITCH_ABC_TYPE_WRITE_REPLACE
- When the callback function is called with SWITCH_ABC_TYPE_READ, I'm doing a switch_core_media_bug_read to copy all media to a switch_frame_t. To then get the raw data, I see in many examples that the size of the frame is retrieved by "(switch_size_t) frame.datalen / 2". Why the division by two ?
- I thought that frame.data contained a un-encoded version of the RTP packet, but the datalen seems to differ when I'm calling in over g711 or g722. What format is frame.data ?
Thanks a lot !
regards,
Leon
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-- Anthony Minessale II FreeSWITCH http://www.freeswitch.org/ ClueCon http://www.cluecon.com/ Twitter: http://twitter.com/FreeSWITCH_wire AIM: anthm MSN:anthony_minessale@hotmail.com <MSN%3Aanthony_minessale@hotmail.com> GTALK/JABBER/PAYPAL:anthony.minessale@gmail.com<PAYPAL%3Aanthony.minessale@gmail.com> IRC: irc.freenode.net #freeswitch FreeSWITCH Developer Conference sip:888@conference.freeswitch.org <sip%3A888@conference.freeswitch.org> iax:guest@conference.freeswitch.org/888 googletalk:conf+888@conference.freeswitch.org<googletalk%3Aconf%2B888@conference.freeswitch.org> pstn:213-799-1400
Thanks, that's precisely the info I need :) On Thu, 2009-10-01 at 16:39 -0500, Anthony Minessale wrote:
READ_STREAM and WRITE_STREAM give you muxed stream of both directions at once by buffering it.
READ_REPLACE and WRITE_REPLACE give you the packets as they happen in that particular direction with added capability that you can write new data into the frame to take it's place.
The format in a media bug is always raw signed linear.
datalen is the size in bytes of the decoded payload.
g711 decodes to 320 bytes per 20ms packet g722 decodes to twice that, 640, since it's 16lhz audio.
On Thu, Oct 1, 2009 at 4:45 AM, Leon de Rooij <leon@scarlet-internet.nl> wrote: Hi all,
I'm trying to make a legal intercept module. My first attempt was to get the raw RTP packets from switch_frame_t, but they don't seem to be available. My second attempt is to get the raw pcm data from the frames, which seems to work. I still have a few questions though:
- On setting the mediabug (switch_core_media_bug_add), I can pass an enum. Is there a difference between SMBF_BOTH (0) or SMBF_READ_STREAM | SMBF_WRITE_STREAM (1+2=3) ?
- In the callback function passed to the bug, what does each of the following switch_abc_type_t mean ? At first I assumed that READ and WRITE state the direction of the media, but some recording functions only use the READ so that can't be true.
SWITCH_ABC_TYPE_INIT SWITCH_ABC_TYPE_READ_PING SWITCH_ABC_TYPE_CLOSE SWITCH_ABC_TYPE_READ SWITCH_ABC_TYPE_WRITE SWITCH_ABC_TYPE_READ_REPLACE SWITCH_ABC_TYPE_WRITE_REPLACE
- When the callback function is called with SWITCH_ABC_TYPE_READ, I'm doing a switch_core_media_bug_read to copy all media to a switch_frame_t. To then get the raw data, I see in many examples that the size of the frame is retrieved by "(switch_size_t) frame.datalen / 2". Why the division by two ?
- I thought that frame.data contained a un-encoded version of the RTP packet, but the datalen seems to differ when I'm calling in over g711 or g722. What format is frame.data ?
Thanks a lot !
regards,
Leon
_______________________________________________ FreeSWITCH-dev mailing list FreeSWITCH-dev@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev http://www.freeswitch.org
-- Anthony Minessale II
FreeSWITCH http://www.freeswitch.org/ ClueCon http://www.cluecon.com/ Twitter: http://twitter.com/FreeSWITCH_wire
AIM: anthm MSN:anthony_minessale@hotmail.com GTALK/JABBER/PAYPAL:anthony.minessale@gmail.com IRC: irc.freenode.net #freeswitch
FreeSWITCH Developer Conference sip:888@conference.freeswitch.org iax:guest@conference.freeswitch.org/888 googletalk:conf+888@conference.freeswitch.org pstn:213-799-1400 _______________________________________________ FreeSWITCH-dev mailing list FreeSWITCH-dev@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev http://www.freeswitch.org
participants (2)
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Anthony Minessale
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Leon de Rooij