Incorrect music playback after transcoding

I'm trying to transcode AAC files to MP3 and the following are lines added to profiles.xml for the audio playback device:

<Profile id="mp3Radio" name="mp3 only iRadio" extendsProfileId="1">
<ProtocolInfo>simple</ProtocolInfo>
<Transcoding>
<Audio targetContainer="mp3">
<Matches container="mp4" />
</Audio>
</Transcoding>
</Profile>

I can find the corresponding STF file in the folder for transcoded files. No problems with this file. I can play it as MP3 via VLC.
But the voice from my playback device is very strange: the temp is too fast and frequent stuttering.

The following is from serviio.log:

2013-01-02 17:42:47,803 INFO [WebServer] WebServer starting on port 8895
2013-01-02 17:42:47,805 INFO [DiscoverySSDPMessageListener] Starting DiscoverySSDPMessageListener using interface en0 (en0) and address 192.168.0.5, timeout = 0
2013-01-02 17:42:47,805 INFO [EventSubscriptionExpirationChecker] Starting EventSubscriptionExpirationChecker
2013-01-02 17:42:47,805 INFO [EventDispatcher] Starting EventDispatcher
2013-01-02 17:42:47,805 INFO [DiscoveryAdvertisementNotifier] Starting DiscoveryAdvertisementNotifier
2013-01-02 17:42:47,805 INFO [RendererSearchSender] Searching for Renderer devices, will multicast on 1 NICs
2013-01-02 17:44:27,513 WARN [EventDispatcher] Couldn't send event message for subscription b710cde2-3cd6-48de-8a40-5de57ca55cab, will keep trying until subscription expires
2013-01-02 17:45:14,105 WARN [EventDispatcher] Couldn't send event message for subscription b710cde2-3cd6-48de-8a40-5de57ca55cab, will keep trying until subscription expires
2013-01-02 17:45:46,676 WARN [EventDispatcher] Couldn't send event message for subscription b710cde2-3cd6-48de-8a40-5de57ca55cab, will keep trying until subscription expires
2013-01-02 17:46:38,913 WARN [ProcessExecutor] Process /Users/amikh/Applications/Serviio/Serviio.app/Contents/Resources/Java/../../MacOS/ffmpeg has a return code of 1! This is a possible error.

Please also note that I start Serviio.app from regular user, not from root or admin

Is it possible to resolve/correct the problem?

[zip]

try to set target bitrate and/or sample rate on the transcoding config

I had already try to change bitrate from 64 to 320 and samplerate 44100 and 48000. I can see this change on display of playback device. But nothing corrected. The playback is too fast (about 50% faster then expected) and stutters are frequent.
At first I tried the following :
<Profile id="mp3Radio" name="mp3 only iRadio" extendsProfileId="1">
<Transcoding>
<Audio targetContainer="mp3" aBitrate="128" aSamplerate="44100">
<Matches container="*" />
</Audio>
</Transcoding>
</Profile>