/**
* Creates a <tt>MediaFormat</tt> for the specified <tt>encoding</tt>, <tt>clockRate</tt>,
* <tt>channels</tt> and set of format parameters. If <tt>encoding</tt> is known to this
* <tt>MediaFormatFactory</tt>, returns a <tt>MediaFormat</tt> which is either an
* <tt>AudioMediaFormat</tt> or a <tt>VideoMediaFormat</tt> instance. Otherwise, returns
* <tt>null</tt>.
*
* @param encoding the well-known encoding (name) to create a <tt>MediaFormat</tt> for
* @param clockRate the clock rate in Hz to create a <tt>MediaFormat</tt> for
* @param frameRate the frame rate in number of frames per second to create a <tt>MediaFormat</tt>
* for
* @param channels the number of available channels (1 for mono, 2 for stereo) if it makes sense
* for the <tt>MediaFormat</tt> with the specified <tt>encoding</tt>; otherwise, ignored
* @param formatParams any codec specific parameters which have been received via SIP/SDP or
* XMPP/Jingle
* @param advancedParams any parameters which have been received via SIP/SDP or XMPP/Jingle
* @return a <tt>MediaFormat</tt> with the specified <tt>encoding</tt>, <tt>clockRate</tt>,
* <tt>channels</tt> and set of format parameters which is either an <tt>AudioMediaFormat</tt>
* or a <tt>VideoMediaFormat</tt> instance if <tt>encoding</tt> is known to this
* <tt>MediaFormatFactory</tt>; otherwise, <tt>null</tt>
* @see MediaFormatFactory#createMediaFormat(String, double, int, float, Map, Map)
*/
public MediaFormat createMediaFormat(
String encoding,
double clockRate,
int channels,
float frameRate,
Map<String, String> formatParams,
Map<String, String> advancedParams) {
MediaFormat mediaFormat = createMediaFormat(encoding, clockRate, channels, formatParams);
if (mediaFormat == null) return null;
/*
* MediaFormatImpl is immutable so if the caller wants to change the
* format parameters and/or the advanced attributes, we'll have to
* create a new MediaFormatImpl.
*/
Map<String, String> formatParameters = null;
Map<String, String> advancedParameters = null;
if ((formatParams != null) && !formatParams.isEmpty()) formatParameters = formatParams;
if ((advancedParams != null) && !advancedParams.isEmpty()) advancedParameters = advancedParams;
if ((formatParameters != null) || (advancedParameters != null)) {
switch (mediaFormat.getMediaType()) {
case AUDIO:
mediaFormat =
new AudioMediaFormatImpl(
((AudioMediaFormatImpl) mediaFormat).getFormat(),
formatParameters,
advancedParameters);
break;
case VIDEO:
VideoMediaFormatImpl videoMediaFormatImpl = (VideoMediaFormatImpl) mediaFormat;
/*
* If the format of VideoMediaFormatImpl is
* a ParameterizedVideoFormat, it's possible for the format
* parameters of that ParameterizedVideoFormat and of the new
* VideoMediaFormatImpl (to be created) to be out of sync. While
* it's not technically perfect, it should be practically safe
* for the format parameters which distinguish VideoFormats with
* the same encoding and clock rate because mediaFormat has
* already been created in sync with formatParams (with respect
* to the format parameters which distinguish VideoFormats with
* the same encoding and clock rate).
*/
mediaFormat =
new VideoMediaFormatImpl(
videoMediaFormatImpl.getFormat(),
videoMediaFormatImpl.getClockRate(),
frameRate,
formatParameters,
advancedParameters);
break;
default:
mediaFormat = null;
}
}
return mediaFormat;
}
/**
* Returns the sequence number to use for a specific RTX packet, which is based on the packet's
* original sequence number.
*
* <p>Because we terminate the RTX format, and with simulcast we might translate RTX packets from
* multiple SSRCs into the same SSRC, we keep count of the RTX packets (and their sequence
* numbers) which we sent for each SSRC.
*
* @param ssrc the SSRC of the RTX stream for the packet.
* @return the sequence number which should be used for the next RTX packet sent using SSRC
* <tt>ssrc</tt>.
*/
private int getNextRtxSequenceNumber(long ssrc) {
Integer seq;
synchronized (rtxSequenceNumbers) {
seq = rtxSequenceNumbers.get(ssrc);
if (seq == null) seq = new Random().nextInt(0xffff);
else seq++;
rtxSequenceNumbers.put(ssrc, seq);
}
return seq;
}
/**
* Notifies this instance that the dynamic payload types of the associated {@link MediaStream}
* have changed.
*/
public void onDynamicPayloadTypesChanged() {
rtxPayloadType = -1;
rtxAssociatedPayloadType = -1;
MediaStream mediaStream = channel.getStream();
Map<Byte, MediaFormat> mediaFormatMap = mediaStream.getDynamicRTPPayloadTypes();
Iterator<Map.Entry<Byte, MediaFormat>> it = mediaFormatMap.entrySet().iterator();
while (it.hasNext() && rtxPayloadType == -1) {
Map.Entry<Byte, MediaFormat> entry = it.next();
MediaFormat format = entry.getValue();
if (!Constants.RTX.equalsIgnoreCase(format.getEncoding())) {
continue;
}
// XXX(gp) we freak out if multiple codecs with RTX support are
// present.
rtxPayloadType = entry.getKey();
rtxAssociatedPayloadType = Byte.parseByte(format.getFormatParameters().get("apt"));
}
}
