gstreamer/ext/avtp/gstavtpcvfpay.h
Ederson de Souza 3b4f3a0b3f avtp: Introduce AVTP CVF payloader element
This patch introduces the AVTP Compressed Video Format (CVF) payloader
specified in IEEE 1722-2016 section 8. Currently, this payload only
supports H.264 encapsulation described in section 8.5.

Is also worth noting that only single NAL units are encapsulated: no
aggregation or fragmentation is performed by the payloader.

An interesting characteristic of CVF H.264 spec is that it defines an
H264_TIMESTAMP, in addition to the AVTP timestamp. The later is
translated to the GST_BUFFER_DTS while the former is translated to the
GST_BUFFER_PTS. From AVTP CVF H.264 spec, it is clear that the AVTP
timestamp is related to the decoding order, while the H264_TIMESTAMP is
an ancillary information to the H.264 decoder.

Upon receiving a buffer containing a group of NAL units, the avtpcvfpay
element will extract each NAL unit and payload them into individual AVTP
packets. The last AVTP packet generated for a group of NAL units will
have the M bit set, so the depayloader is able to properly regroup them.

The exact format of the buffer of NAL units is described on the
'codec_data' capability, which is parsed by the avtpcvfpay, in the same
way done in rtph264pay.

This patch reuses the infra provided by gstavtpbasepayload.c.
2019-07-03 09:59:35 -07:00

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1.9 KiB
C

/*
* GStreamer AVTP Plugin
* Copyright (C) 2019 Intel Corporation
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later
* version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
#ifndef __GST_AVTP_CVF_PAY_H__
#define __GST_AVTP_CVF_PAY_H__
#include <gst/gst.h>
#include "gstavtpbasepayload.h"
G_BEGIN_DECLS
#define GST_TYPE_AVTP_CVF_PAY (gst_avtp_cvf_pay_get_type())
#define GST_AVTP_CVF_PAY(obj) \
(G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_AVTP_CVF_PAY,GstAvtpCvfPay))
#define GST_AVTP_CVF_PAY_CLASS(klass) \
(G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_AVTP_CVF_PAY,GstAvtpCvfPayClass))
#define GST_IS_AVTP_CVF_PAY(obj) \
(G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_AVTP_CVF_PAY))
#define GST_IS_AVTP_CVF_PAY_CLASS(klass) \
(G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_AVTP_CVF_PAY))
typedef struct _GstAvtpCvfPay GstAvtpCvfPay;
typedef struct _GstAvtpCvfPayClass GstAvtpCvfPayClass;
struct _GstAvtpCvfPay
{
GstAvtpBasePayload payload;
GstBuffer *header;
guint mtu;
/* H.264 specific information */
guint8 nal_length_size;
};
struct _GstAvtpCvfPayClass
{
GstAvtpBasePayloadClass parent_class;
};
GType gst_avtp_cvf_pay_get_type (void);
gboolean gst_avtp_cvf_pay_plugin_init (GstPlugin * plugin);
G_END_DECLS
#endif /* __GST_AVTP_CVF_PAY_H__ */