media/libaah_rtp/aah_rx_player_substream.cpp - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "LibAAH_RTP"
 //#define LOG_NDEBUG 0

 #include <utils/Log.h>

 #include <include/avc_utils.h>
 #include <media/stagefright/MediaBuffer.h>
 #include <media/stagefright/MediaDefs.h>
 #include <media/stagefright/MetaData.h>
 #include <media/stagefright/OMXCodec.h>
 #include <media/stagefright/Utils.h>

 #include "aah_rx_player.h"

 namespace android {

 int64_t AAH_RXPlayer::Substream::kAboutToUnderflowThreshold =
     50ull * 1000;

 AAH_RXPlayer::Substream::Substream(uint32_t ssrc, OMXClient& omx) {
     ssrc_ = ssrc;
     substream_details_known_ = false;
     buffer_in_progress_ = NULL;
     status_ = OK;

     decoder_ = new AAH_DecoderPump(omx);
     if (decoder_ == NULL) {
         ALOGE("%s failed to allocate decoder pump!", __PRETTY_FUNCTION__);
     }
     if (OK != decoder_->initCheck()) {
         ALOGE("%s failed to initialize decoder pump!", __PRETTY_FUNCTION__);
     }

     // cleanupBufferInProgress will reset most of the internal state variables.
     // Just need to make sure that buffer_in_progress_ is NULL before calling.
     cleanupBufferInProgress();
 }


 void AAH_RXPlayer::Substream::shutdown() {
     substream_meta_ = NULL;
     status_ = OK;
     cleanupBufferInProgress();
     cleanupDecoder();
 }

 void AAH_RXPlayer::Substream::cleanupBufferInProgress() {
     if (NULL != buffer_in_progress_) {
         buffer_in_progress_->release();
         buffer_in_progress_ = NULL;
     }

     expected_buffer_size_ = 0;
     buffer_filled_ = 0;
     waiting_for_rap_ = true;
 }

 void AAH_RXPlayer::Substream::cleanupDecoder() {
     if (decoder_ != NULL) {
         decoder_->shutdown();
     }
 }

 bool AAH_RXPlayer::Substream::shouldAbort(const char* log_tag) {
     // If we have already encountered a fatal error, do nothing.  We are just
     // waiting for our owner to shut us down now.
     if (OK != status_) {
         ALOGV("Skipping %s, substream has encountered fatal error (%d).",
                 log_tag, status_);
         return true;
     }

     return false;
 }

 void AAH_RXPlayer::Substream::processPayloadStart(uint8_t* buf,
                                                   uint32_t amt,
                                                   int32_t ts_lower) {
     uint32_t min_length = 6;

     if (shouldAbort(__PRETTY_FUNCTION__)) {
         return;
     }

     // Do we have a buffer in progress already?  If so, abort the buffer.  In
     // theory, this should never happen.  If there were a discontinutity in the
     // stream, the discon in the seq_nos at the RTP level should have already
     // triggered a cleanup of the buffer in progress.  To see a problem at this
     // level is an indication either of a bug in the transmitter, or some form
     // of terrible corruption/tampering on the wire.
     if (NULL != buffer_in_progress_) {
         ALOGE("processPayloadStart is aborting payload already in progress.");
         cleanupBufferInProgress();
     }

     // Parse enough of the header to know where we stand.  Since this is a
     // payload start, it should begin with a TRTP header which has to be at
     // least 6 bytes long.
     if (amt < min_length) {
         ALOGV("Discarding payload too short to contain TRTP header (len = %u)",
                 amt);
         return;
     }

     // Check the TRTP version number.
     if (0x01 != buf[0]) {
         ALOGV("Unexpected TRTP version (%u) in header.  Expected %u.",
                 buf[0], 1);
         return;
     }

     // Extract the substream type field and make sure its one we understand (and
     // one that does not conflict with any previously received substream type.
     uint8_t header_type = (buf[1] >> 4) & 0xF;
     switch (header_type) {
         case 0x01:
             // Audio, yay!  Just break.  We understand audio payloads.
             break;
         case 0x02:
             ALOGV("RXed packet with unhandled TRTP header type (Video).");
             return;
         case 0x03:
             ALOGV("RXed packet with unhandled TRTP header type (Subpicture).");
             return;
         case 0x04:
             ALOGV("RXed packet with unhandled TRTP header type (Control).");
             return;
         default:
             ALOGV("RXed packet with unhandled TRTP header type (%u).",
                     header_type);
             return;
     }

     if (substream_details_known_ && (header_type != substream_type_)) {
         ALOGV("RXed TRTP Payload for SSRC=0x%08x where header type (%u) does not"
               " match previously received header type (%u)",
               ssrc_, header_type, substream_type_);
         return;
     }

     // Check the flags to see if there is another 32 bits of timestamp present.
     uint32_t trtp_header_len = 6;
     bool ts_valid = buf[1] & 0x1;
     if (ts_valid) {
         min_length += 4;
         trtp_header_len += 4;
         if (amt < min_length) {
             ALOGV("Discarding payload too short to contain TRTP timestamp"
                   " (len = %u)", amt);
             return;
         }
     }

     // Extract the TRTP length field and sanity check it.
     uint32_t trtp_len;
     trtp_len = (static_cast<uint32_t>(buf[2]) << 24) |
         (static_cast<uint32_t>(buf[3]) << 16) |
         (static_cast<uint32_t>(buf[4]) <<  8) |
         static_cast<uint32_t>(buf[5]);
     if (trtp_len < min_length) {
         ALOGV("TRTP length (%u) is too short to be valid.  Must be at least %u"
               " bytes.", trtp_len, min_length);
         return;
     }

     // Extract the rest of the timestamp field if valid.
     int64_t ts = 0;
     uint32_t parse_offset = 6;
     if (ts_valid) {
         ts = (static_cast<int64_t>(buf[parse_offset    ]) << 56) |
             (static_cast<int64_t>(buf[parse_offset + 1]) << 48) |
             (static_cast<int64_t>(buf[parse_offset + 2]) << 40) |
             (static_cast<int64_t>(buf[parse_offset + 3]) << 32);
         ts |= ts_lower;
         parse_offset += 4;
     }

     // Check the flags to see if there is another 24 bytes of timestamp
     // transformation present.
     if (buf[1] & 0x2) {
         min_length += 24;
         parse_offset += 24;
         trtp_header_len += 24;
         if (amt < min_length) {
             ALOGV("Discarding payload too short to contain TRTP timestamp"
                   " transformation (len = %u)", amt);
             return;
         }
     }

     // TODO : break the parsing into individual parsers for the different
     // payload types (audio, video, etc).
     //
     // At this point in time, we know that this is audio.  Go ahead and parse
     // the basic header, check the codec type, and find the payload portion of
     // the packet.
     min_length += 3;
     if (trtp_len < min_length) {
         ALOGV("TRTP length (%u) is too short to be a valid audio payload.  Must"
               " be at least %u bytes.", trtp_len, min_length);
         return;
     }

     if (amt < min_length) {
         ALOGV("TRTP porttion of RTP payload (%u bytes) too small to contain"
               " entire TRTP header.  TRTP does not currently support fragmenting"
               " TRTP headers across RTP payloads", amt);
         return;
     }

     uint8_t codec_type = buf[parse_offset    ];
     uint8_t flags      = buf[parse_offset + 1];
     uint8_t volume     = buf[parse_offset + 2];
     parse_offset += 3;
     trtp_header_len += 3;

     if (!setupSubstreamType(header_type, codec_type)) {
         return;
     }

     if (decoder_ != NULL) {
         decoder_->setRenderVolume(volume);
     }

     // TODO : move all of the constant flag and offset definitions for TRTP up
     // into some sort of common header file.
     if (waiting_for_rap_ && !(flags & 0x08)) {
         ALOGV("Dropping non-RAP TRTP Audio Payload while waiting for RAP.");
         return;
     }

     if (flags & 0x10) {
         ALOGV("Dropping TRTP Audio Payload with aux codec data present (only"
               " handle MP3 right now, and it has no aux data)");
         return;
     }

     // OK - everything left is just payload.  Compute the payload size, start
     // the buffer in progress and pack as much payload as we can into it.  If
     // the payload is finished once we are done, go ahead and send the payload
     // to the decoder.
     expected_buffer_size_ = trtp_len - trtp_header_len;
     if (!expected_buffer_size_) {
         ALOGV("Dropping TRTP Audio Payload with 0 Access Unit length");
         return;
     }

     CHECK(amt >= trtp_header_len);
     uint32_t todo = amt - trtp_header_len;
     if (expected_buffer_size_ < todo) {
         ALOGV("Extra data (%u > %u) present in initial TRTP Audio Payload;"
               " dropping payload.", todo, expected_buffer_size_);
         return;
     }

     buffer_filled_ = 0;
     buffer_in_progress_ = new MediaBuffer(expected_buffer_size_);
     if ((NULL == buffer_in_progress_) ||
             (NULL == buffer_in_progress_->data())) {
         ALOGV("Failed to allocate MediaBuffer of length %u",
                 expected_buffer_size_);
         cleanupBufferInProgress();
         return;
     }

     sp<MetaData> meta = buffer_in_progress_->meta_data();
     if (meta == NULL) {
         ALOGV("Missing metadata structure in allocated MediaBuffer; dropping"
               " payload");
         cleanupBufferInProgress();
         return;
     }

     // TODO : set this based on the codec type indicated in the TRTP stream.
     // Right now, we only support MP3, so the choice is obvious.
     meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_MPEG);
     if (ts_valid) {
         meta->setInt64(kKeyTime, ts);
     }

     if (amt > 0) {
         uint8_t* tgt =
             reinterpret_cast<uint8_t*>(buffer_in_progress_->data());
         memcpy(tgt + buffer_filled_, buf + trtp_header_len, todo);
         buffer_filled_ += amt;
     }

     if (buffer_filled_ >= expected_buffer_size_) {
         processCompletedBuffer();
     }
 }

 void AAH_RXPlayer::Substream::processPayloadCont(uint8_t* buf,
                                                  uint32_t amt) {
     if (shouldAbort(__PRETTY_FUNCTION__)) {
         return;
     }

     if (NULL == buffer_in_progress_) {
         ALOGV("TRTP Receiver skipping payload continuation; no buffer currently"
               " in progress.");
         return;
     }

     CHECK(buffer_filled_ < expected_buffer_size_);
     uint32_t buffer_left = expected_buffer_size_ - buffer_filled_;
     if (amt > buffer_left) {
         ALOGV("Extra data (%u > %u) present in continued TRTP Audio Payload;"
               " dropping payload.", amt, buffer_left);
         cleanupBufferInProgress();
         return;
     }

     if (amt > 0) {
         uint8_t* tgt =
             reinterpret_cast<uint8_t*>(buffer_in_progress_->data());
         memcpy(tgt + buffer_filled_, buf, amt);
         buffer_filled_ += amt;
     }

     if (buffer_filled_ >= expected_buffer_size_) {
         processCompletedBuffer();
     }
 }

 void AAH_RXPlayer::Substream::processCompletedBuffer() {
     const uint8_t* buffer_data = NULL;
     int sample_rate;
     int channel_count;
     size_t frame_size;
     status_t res;

     CHECK(NULL != buffer_in_progress_);

     if (decoder_ == NULL) {
         ALOGV("Dropping complete buffer, no decoder pump allocated");
         goto bailout;
     }

     buffer_data = reinterpret_cast<const uint8_t*>(buffer_in_progress_->data());
     if (buffer_in_progress_->size() < 4) {
         ALOGV("MP3 payload too short to contain header, dropping payload.");
         goto bailout;
     }

     // Extract the channel count and the sample rate from the MP3 header.  The
     // stagefright MP3 requires that these be delivered before decoing can
     // begin.
     if (!GetMPEGAudioFrameSize(U32_AT(buffer_data),
                                &frame_size,
                                &sample_rate,
                                &channel_count,
                                NULL,
                                NULL)) {
         ALOGV("Failed to parse MP3 header in payload, droping payload.");
         goto bailout;
     }


     // Make sure that our substream metadata is set up properly.  If there has
     // been a format change, be sure to reset the underlying decoder.  In
     // stagefright, it seems like the only way to do this is to destroy and
     // recreate the decoder.
     if (substream_meta_ == NULL) {
         substream_meta_ = new MetaData();

         if (substream_meta_ == NULL) {
             ALOGE("Failed to allocate MetaData structure for substream");
             goto bailout;
         }

         substream_meta_->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_MPEG);
         substream_meta_->setInt32  (kKeyChannelCount, channel_count);
         substream_meta_->setInt32  (kKeySampleRate,   sample_rate);
     } else {
         int32_t prev_sample_rate;
         int32_t prev_channel_count;
         substream_meta_->findInt32(kKeySampleRate,   &prev_sample_rate);
         substream_meta_->findInt32(kKeyChannelCount, &prev_channel_count);

         if ((prev_channel_count != channel_count) ||
             (prev_sample_rate   != sample_rate)) {
             ALOGW("Format change detected, forcing decoder reset.");
             cleanupDecoder();

             substream_meta_->setInt32(kKeyChannelCount, channel_count);
             substream_meta_->setInt32(kKeySampleRate,   sample_rate);
         }
     }

     // If our decoder has not be set up, do so now.
     res = decoder_->init(substream_meta_);
     if (OK != res) {
         ALOGE("Failed to init decoder (res = %d)", res);
         cleanupDecoder();
         substream_meta_ = NULL;
         goto bailout;
     }

     // Queue the payload for decode.
     res = decoder_->queueForDecode(buffer_in_progress_);

     if (res != OK) {
         ALOGD("Failed to queue payload for decode, resetting decoder pump!"
               " (res = %d)", res);
         status_ = res;
         cleanupDecoder();
         cleanupBufferInProgress();
     }

     // NULL out buffer_in_progress before calling the cleanup helper.
     //
     // MediaBuffers use something of a hybrid ref-counting pattern which prevent
     // the AAH_DecoderPump's input queue from adding their own reference to the
     // MediaBuffer.  MediaBuffers start life with a reference count of 0, as
     // well as an observer which starts as NULL.  Before being given an
     // observer, the ref count cannot be allowed to become non-zero as it will
     // cause calls to release() to assert.  Basically, before a MediaBuffer has
     // an observer, they behave like non-ref counted obects where release()
     // serves the roll of delete.  After a MediaBuffer has an observer, they
     // become more like ref counted objects where add ref and release can be
     // used, and when the ref count hits zero, the MediaBuffer is handed off to
     // the observer.
     //
     // Given all of this, when we give the buffer to the decoder pump to wait in
     // the to-be-processed queue, the decoder cannot add a ref to the buffer as
     // it would in a traditional ref counting system.  Instead it needs to
     // "steal" the non-existent ref.  In the case of queue failure, we need to
     // make certain to release this non-existent reference so that the buffer is
     // cleaned up during the cleanupBufferInProgress helper.  In the case of a
     // successful queue operation, we need to make certain that the
     // cleanupBufferInProgress helper does not release the buffer since it needs
     // to remain alive in the queue.  We acomplish this by NULLing out the
     // buffer pointer before calling the cleanup helper.
     buffer_in_progress_ = NULL;

 bailout:
     cleanupBufferInProgress();
 }


 void AAH_RXPlayer::Substream::processTSTransform(const LinearTransform& trans) {
     if (decoder_ != NULL) {
         decoder_->setRenderTSTransform(trans);
     }
 }

 bool AAH_RXPlayer::Substream::isAboutToUnderflow() {
     if (decoder_ == NULL) {
         return false;
     }

     return decoder_->isAboutToUnderflow(kAboutToUnderflowThreshold);
 }

 bool AAH_RXPlayer::Substream::setupSubstreamType(uint8_t substream_type,
                                                  uint8_t codec_type) {
     // Sanity check the codec type.  Right now we only support MP3.  Also check
     // for conflicts with previously delivered codec types.
     if (substream_details_known_ && (codec_type != codec_type_)) {
         ALOGV("RXed TRTP Payload for SSRC=0x%08x where codec type (%u) does not"
               " match previously received codec type (%u)",
               ssrc_, codec_type, codec_type_);
         return false;
     }

     if (codec_type != 0x03) {
         ALOGV("RXed TRTP Audio Payload for SSRC=0x%08x with unsupported codec"
               " type (%u)", ssrc_, codec_type);
         return false;
     }

     if (!substream_details_known_) {
         substream_type_ = substream_type;
         codec_type_ = codec_type;
         substream_details_known_ = true;
     }

     return true;
 }

 }  // namespace android
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "LibAAH_RTP"
	//#define LOG_NDEBUG 0

	#include <utils/Log.h>

	#include <include/avc_utils.h>
	#include <media/stagefright/MediaBuffer.h>
	#include <media/stagefright/MediaDefs.h>
	#include <media/stagefright/MetaData.h>
	#include <media/stagefright/OMXCodec.h>
	#include <media/stagefright/Utils.h>

	#include "aah_rx_player.h"

	namespace android {

	int64_t AAH_RXPlayer::Substream::kAboutToUnderflowThreshold =
	50ull * 1000;

	AAH_RXPlayer::Substream::Substream(uint32_t ssrc, OMXClient& omx) {
	ssrc_ = ssrc;
	substream_details_known_ = false;
	buffer_in_progress_ = NULL;
	status_ = OK;

	decoder_ = new AAH_DecoderPump(omx);
	if (decoder_ == NULL) {
	ALOGE("%s failed to allocate decoder pump!", __PRETTY_FUNCTION__);
	}
	if (OK != decoder_->initCheck()) {
	ALOGE("%s failed to initialize decoder pump!", __PRETTY_FUNCTION__);
	}

	// cleanupBufferInProgress will reset most of the internal state variables.
	// Just need to make sure that buffer_in_progress_ is NULL before calling.
	cleanupBufferInProgress();
	}


	void AAH_RXPlayer::Substream::shutdown() {
	substream_meta_ = NULL;
	status_ = OK;
	cleanupBufferInProgress();
	cleanupDecoder();
	}

	void AAH_RXPlayer::Substream::cleanupBufferInProgress() {
	if (NULL != buffer_in_progress_) {
	buffer_in_progress_->release();
	buffer_in_progress_ = NULL;
	}

	expected_buffer_size_ = 0;
	buffer_filled_ = 0;
	waiting_for_rap_ = true;
	}

	void AAH_RXPlayer::Substream::cleanupDecoder() {
	if (decoder_ != NULL) {
	decoder_->shutdown();
	}
	}

	bool AAH_RXPlayer::Substream::shouldAbort(const char* log_tag) {
	// If we have already encountered a fatal error, do nothing. We are just
	// waiting for our owner to shut us down now.
	if (OK != status_) {
	ALOGV("Skipping %s, substream has encountered fatal error (%d).",
	log_tag, status_);
	return true;
	}

	return false;
	}

	void AAH_RXPlayer::Substream::processPayloadStart(uint8_t* buf,
	uint32_t amt,
	int32_t ts_lower) {
	uint32_t min_length = 6;

	if (shouldAbort(__PRETTY_FUNCTION__)) {
	return;
	}

	// Do we have a buffer in progress already? If so, abort the buffer. In
	// theory, this should never happen. If there were a discontinutity in the
	// stream, the discon in the seq_nos at the RTP level should have already
	// triggered a cleanup of the buffer in progress. To see a problem at this
	// level is an indication either of a bug in the transmitter, or some form
	// of terrible corruption/tampering on the wire.
	if (NULL != buffer_in_progress_) {
	ALOGE("processPayloadStart is aborting payload already in progress.");
	cleanupBufferInProgress();
	}

	// Parse enough of the header to know where we stand. Since this is a
	// payload start, it should begin with a TRTP header which has to be at
	// least 6 bytes long.
	if (amt < min_length) {
	ALOGV("Discarding payload too short to contain TRTP header (len = %u)",
	amt);
	return;
	}

	// Check the TRTP version number.
	if (0x01 != buf[0]) {
	ALOGV("Unexpected TRTP version (%u) in header. Expected %u.",
	buf[0], 1);
	return;
	}

	// Extract the substream type field and make sure its one we understand (and
	// one that does not conflict with any previously received substream type.
	uint8_t header_type = (buf[1] >> 4) & 0xF;
	switch (header_type) {
	case 0x01:
	// Audio, yay! Just break. We understand audio payloads.
	break;
	case 0x02:
	ALOGV("RXed packet with unhandled TRTP header type (Video).");
	return;
	case 0x03:
	ALOGV("RXed packet with unhandled TRTP header type (Subpicture).");
	return;
	case 0x04:
	ALOGV("RXed packet with unhandled TRTP header type (Control).");
	return;
	default:
	ALOGV("RXed packet with unhandled TRTP header type (%u).",
	header_type);
	return;
	}

	if (substream_details_known_ && (header_type != substream_type_)) {
	ALOGV("RXed TRTP Payload for SSRC=0x%08x where header type (%u) does not"
	" match previously received header type (%u)",
	ssrc_, header_type, substream_type_);
	return;
	}

	// Check the flags to see if there is another 32 bits of timestamp present.
	uint32_t trtp_header_len = 6;
	bool ts_valid = buf[1] & 0x1;
	if (ts_valid) {
	min_length += 4;
	trtp_header_len += 4;
	if (amt < min_length) {
	ALOGV("Discarding payload too short to contain TRTP timestamp"
	" (len = %u)", amt);
	return;
	}
	}

	// Extract the TRTP length field and sanity check it.
	uint32_t trtp_len;
	trtp_len = (static_cast<uint32_t>(buf[2]) << 24) \|
	(static_cast<uint32_t>(buf[3]) << 16) \|
	(static_cast<uint32_t>(buf[4]) << 8) \|
	static_cast<uint32_t>(buf[5]);
	if (trtp_len < min_length) {
	ALOGV("TRTP length (%u) is too short to be valid. Must be at least %u"
	" bytes.", trtp_len, min_length);
	return;
	}

	// Extract the rest of the timestamp field if valid.
	int64_t ts = 0;
	uint32_t parse_offset = 6;
	if (ts_valid) {
	ts = (static_cast<int64_t>(buf[parse_offset ]) << 56) \|
	(static_cast<int64_t>(buf[parse_offset + 1]) << 48) \|
	(static_cast<int64_t>(buf[parse_offset + 2]) << 40) \|
	(static_cast<int64_t>(buf[parse_offset + 3]) << 32);
	ts \|= ts_lower;
	parse_offset += 4;
	}

	// Check the flags to see if there is another 24 bytes of timestamp
	// transformation present.
	if (buf[1] & 0x2) {
	min_length += 24;
	parse_offset += 24;
	trtp_header_len += 24;
	if (amt < min_length) {
	ALOGV("Discarding payload too short to contain TRTP timestamp"
	" transformation (len = %u)", amt);
	return;
	}
	}

	// TODO : break the parsing into individual parsers for the different
	// payload types (audio, video, etc).
	//
	// At this point in time, we know that this is audio. Go ahead and parse
	// the basic header, check the codec type, and find the payload portion of
	// the packet.
	min_length += 3;
	if (trtp_len < min_length) {
	ALOGV("TRTP length (%u) is too short to be a valid audio payload. Must"
	" be at least %u bytes.", trtp_len, min_length);
	return;
	}

	if (amt < min_length) {
	ALOGV("TRTP porttion of RTP payload (%u bytes) too small to contain"
	" entire TRTP header. TRTP does not currently support fragmenting"
	" TRTP headers across RTP payloads", amt);
	return;
	}

	uint8_t codec_type = buf[parse_offset ];
	uint8_t flags = buf[parse_offset + 1];
	uint8_t volume = buf[parse_offset + 2];
	parse_offset += 3;
	trtp_header_len += 3;

	if (!setupSubstreamType(header_type, codec_type)) {
	return;
	}

	if (decoder_ != NULL) {
	decoder_->setRenderVolume(volume);
	}

	// TODO : move all of the constant flag and offset definitions for TRTP up
	// into some sort of common header file.
	if (waiting_for_rap_ && !(flags & 0x08)) {
	ALOGV("Dropping non-RAP TRTP Audio Payload while waiting for RAP.");
	return;
	}

	if (flags & 0x10) {
	ALOGV("Dropping TRTP Audio Payload with aux codec data present (only"
	" handle MP3 right now, and it has no aux data)");
	return;
	}

	// OK - everything left is just payload. Compute the payload size, start
	// the buffer in progress and pack as much payload as we can into it. If
	// the payload is finished once we are done, go ahead and send the payload
	// to the decoder.
	expected_buffer_size_ = trtp_len - trtp_header_len;
	if (!expected_buffer_size_) {
	ALOGV("Dropping TRTP Audio Payload with 0 Access Unit length");
	return;
	}

	CHECK(amt >= trtp_header_len);
	uint32_t todo = amt - trtp_header_len;
	if (expected_buffer_size_ < todo) {
	ALOGV("Extra data (%u > %u) present in initial TRTP Audio Payload;"
	" dropping payload.", todo, expected_buffer_size_);
	return;
	}

	buffer_filled_ = 0;
	buffer_in_progress_ = new MediaBuffer(expected_buffer_size_);
	if ((NULL == buffer_in_progress_) \|\|
	(NULL == buffer_in_progress_->data())) {
	ALOGV("Failed to allocate MediaBuffer of length %u",
	expected_buffer_size_);
	cleanupBufferInProgress();
	return;
	}

	sp<MetaData> meta = buffer_in_progress_->meta_data();
	if (meta == NULL) {
	ALOGV("Missing metadata structure in allocated MediaBuffer; dropping"
	" payload");
	cleanupBufferInProgress();
	return;
	}

	// TODO : set this based on the codec type indicated in the TRTP stream.
	// Right now, we only support MP3, so the choice is obvious.
	meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_MPEG);
	if (ts_valid) {
	meta->setInt64(kKeyTime, ts);
	}

	if (amt > 0) {
	uint8_t* tgt =
	reinterpret_cast<uint8_t*>(buffer_in_progress_->data());
	memcpy(tgt + buffer_filled_, buf + trtp_header_len, todo);
	buffer_filled_ += amt;
	}

	if (buffer_filled_ >= expected_buffer_size_) {
	processCompletedBuffer();
	}
	}

	void AAH_RXPlayer::Substream::processPayloadCont(uint8_t* buf,
	uint32_t amt) {
	if (shouldAbort(__PRETTY_FUNCTION__)) {
	return;
	}

	if (NULL == buffer_in_progress_) {
	ALOGV("TRTP Receiver skipping payload continuation; no buffer currently"
	" in progress.");
	return;
	}

	CHECK(buffer_filled_ < expected_buffer_size_);
	uint32_t buffer_left = expected_buffer_size_ - buffer_filled_;
	if (amt > buffer_left) {
	ALOGV("Extra data (%u > %u) present in continued TRTP Audio Payload;"
	" dropping payload.", amt, buffer_left);
	cleanupBufferInProgress();
	return;
	}

	if (amt > 0) {
	uint8_t* tgt =
	reinterpret_cast<uint8_t*>(buffer_in_progress_->data());
	memcpy(tgt + buffer_filled_, buf, amt);
	buffer_filled_ += amt;
	}

	if (buffer_filled_ >= expected_buffer_size_) {
	processCompletedBuffer();
	}
	}

	void AAH_RXPlayer::Substream::processCompletedBuffer() {
	const uint8_t* buffer_data = NULL;
	int sample_rate;
	int channel_count;
	size_t frame_size;
	status_t res;

	CHECK(NULL != buffer_in_progress_);

	if (decoder_ == NULL) {
	ALOGV("Dropping complete buffer, no decoder pump allocated");
	goto bailout;
	}

	buffer_data = reinterpret_cast<const uint8_t*>(buffer_in_progress_->data());
	if (buffer_in_progress_->size() < 4) {
	ALOGV("MP3 payload too short to contain header, dropping payload.");
	goto bailout;
	}

	// Extract the channel count and the sample rate from the MP3 header. The
	// stagefright MP3 requires that these be delivered before decoing can
	// begin.
	if (!GetMPEGAudioFrameSize(U32_AT(buffer_data),
	&frame_size,
	&sample_rate,
	&channel_count,
	NULL,
	NULL)) {
	ALOGV("Failed to parse MP3 header in payload, droping payload.");
	goto bailout;
	}


	// Make sure that our substream metadata is set up properly. If there has
	// been a format change, be sure to reset the underlying decoder. In
	// stagefright, it seems like the only way to do this is to destroy and
	// recreate the decoder.
	if (substream_meta_ == NULL) {
	substream_meta_ = new MetaData();

	if (substream_meta_ == NULL) {
	ALOGE("Failed to allocate MetaData structure for substream");
	goto bailout;
	}

	substream_meta_->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_MPEG);
	substream_meta_->setInt32 (kKeyChannelCount, channel_count);
	substream_meta_->setInt32 (kKeySampleRate, sample_rate);
	} else {
	int32_t prev_sample_rate;
	int32_t prev_channel_count;
	substream_meta_->findInt32(kKeySampleRate, &prev_sample_rate);
	substream_meta_->findInt32(kKeyChannelCount, &prev_channel_count);

	if ((prev_channel_count != channel_count) \|\|
	(prev_sample_rate != sample_rate)) {
	ALOGW("Format change detected, forcing decoder reset.");
	cleanupDecoder();

	substream_meta_->setInt32(kKeyChannelCount, channel_count);
	substream_meta_->setInt32(kKeySampleRate, sample_rate);
	}
	}

	// If our decoder has not be set up, do so now.
	res = decoder_->init(substream_meta_);
	if (OK != res) {
	ALOGE("Failed to init decoder (res = %d)", res);
	cleanupDecoder();
	substream_meta_ = NULL;
	goto bailout;
	}

	// Queue the payload for decode.
	res = decoder_->queueForDecode(buffer_in_progress_);

	if (res != OK) {
	ALOGD("Failed to queue payload for decode, resetting decoder pump!"
	" (res = %d)", res);
	status_ = res;
	cleanupDecoder();
	cleanupBufferInProgress();
	}

	// NULL out buffer_in_progress before calling the cleanup helper.
	//
	// MediaBuffers use something of a hybrid ref-counting pattern which prevent
	// the AAH_DecoderPump's input queue from adding their own reference to the
	// MediaBuffer. MediaBuffers start life with a reference count of 0, as
	// well as an observer which starts as NULL. Before being given an
	// observer, the ref count cannot be allowed to become non-zero as it will
	// cause calls to release() to assert. Basically, before a MediaBuffer has
	// an observer, they behave like non-ref counted obects where release()
	// serves the roll of delete. After a MediaBuffer has an observer, they
	// become more like ref counted objects where add ref and release can be
	// used, and when the ref count hits zero, the MediaBuffer is handed off to
	// the observer.
	//
	// Given all of this, when we give the buffer to the decoder pump to wait in
	// the to-be-processed queue, the decoder cannot add a ref to the buffer as
	// it would in a traditional ref counting system. Instead it needs to
	// "steal" the non-existent ref. In the case of queue failure, we need to
	// make certain to release this non-existent reference so that the buffer is
	// cleaned up during the cleanupBufferInProgress helper. In the case of a
	// successful queue operation, we need to make certain that the
	// cleanupBufferInProgress helper does not release the buffer since it needs
	// to remain alive in the queue. We acomplish this by NULLing out the
	// buffer pointer before calling the cleanup helper.
	buffer_in_progress_ = NULL;

	bailout:
	cleanupBufferInProgress();
	}


	void AAH_RXPlayer::Substream::processTSTransform(const LinearTransform& trans) {
	if (decoder_ != NULL) {
	decoder_->setRenderTSTransform(trans);
	}
	}

	bool AAH_RXPlayer::Substream::isAboutToUnderflow() {
	if (decoder_ == NULL) {
	return false;
	}

	return decoder_->isAboutToUnderflow(kAboutToUnderflowThreshold);
	}

	bool AAH_RXPlayer::Substream::setupSubstreamType(uint8_t substream_type,
	uint8_t codec_type) {
	// Sanity check the codec type. Right now we only support MP3. Also check
	// for conflicts with previously delivered codec types.
	if (substream_details_known_ && (codec_type != codec_type_)) {
	ALOGV("RXed TRTP Payload for SSRC=0x%08x where codec type (%u) does not"
	" match previously received codec type (%u)",
	ssrc_, codec_type, codec_type_);
	return false;
	}

	if (codec_type != 0x03) {
	ALOGV("RXed TRTP Audio Payload for SSRC=0x%08x with unsupported codec"
	" type (%u)", ssrc_, codec_type);
	return false;
	}

	if (!substream_details_known_) {
	substream_type_ = substream_type;
	codec_type_ = codec_type;
	substream_details_known_ = true;
	}

	return true;
	}

	} // namespace android