Re: [RFC, WIP, v4 09/11] media: vidtv: implement a PES packetizer

[Mauro Carvalho Chehab <mchehab+huawei@kernel.org>]

Em Sat,  2 May 2020 00:22:14 -0300
"Daniel W. S. Almeida" <dwlsalmeida@gmail.com> escreveu:

> From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
> 
> Implement the PES logic to convert encoder data into MPEG TS packets.
> These TS packets can then be fed into a TS multiplexer and eventually
> into userspace.
> 
> Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> ---
>  drivers/media/test-drivers/vidtv/Makefile     |   2 +-
>  .../media/test-drivers/vidtv/vidtv_common.c   |   7 +
>  .../media/test-drivers/vidtv/vidtv_common.h   |   2 +
>  drivers/media/test-drivers/vidtv/vidtv_pes.c  | 429 ++++++++++++++++++
>  drivers/media/test-drivers/vidtv/vidtv_pes.h  | 185 ++++++++
>  5 files changed, 624 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/media/test-drivers/vidtv/vidtv_pes.c
>  create mode 100644 drivers/media/test-drivers/vidtv/vidtv_pes.h
> 
> diff --git a/drivers/media/test-drivers/vidtv/Makefile b/drivers/media/test-drivers/vidtv/Makefile
> index e4f744aa53136..e3a6540f50e87 100644
> --- a/drivers/media/test-drivers/vidtv/Makefile
> +++ b/drivers/media/test-drivers/vidtv/Makefile
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
>  vidtv_demod-objs := vidtv_common.o
> -vidtv_bridge-objs := vidtv_common.o vidtv_ts.o vidtv_psi.o
> +vidtv_bridge-objs := vidtv_common.o vidtv_ts.o vidtv_psi.o vidtv_pes.o
>  
>  obj-$(CONFIG_DVB_VIDTV)	+= vidtv_tuner.o vidtv_demod.o vidtv_bridge.o
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_common.c b/drivers/media/test-drivers/vidtv/vidtv_common.c
> index 28f10630499a9..b1412b497e1e3 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_common.c
> +++ b/drivers/media/test-drivers/vidtv/vidtv_common.c
> @@ -42,3 +42,10 @@ u32 vidtv_memset(void *to,
>  	memset(to, c, len);
>  	return len;
>  }
> +
> +u64 vidtv_extract_bits(u64 value, u8 start_bit, u8 nbits)
> +{
> +	u64  mask = ((1 << nbits) - 1) << start_bit;
> +
> +	return value & mask;
> +}


There are macros already for it, like:

	include/linux/bits.h:#define BIT_MASK(nr)		(UL(1) << ((nr) % BITS_PER_LONG))

So, please stick with the existing code there, as defining driver-specific
stuff like that is usually painful and may lead into errors.

(Btw, your "mask" definition doesn't work with u64)

> diff --git a/drivers/media/test-drivers/vidtv/vidtv_common.h b/drivers/media/test-drivers/vidtv/vidtv_common.h
> index 64072c010dc66..3b68f95c5f6c8 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_common.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_common.h
> @@ -25,4 +25,6 @@ u32 vidtv_memset(void *to,
>  		 u32 offset,
>  		 u32 buf_sz);
>  
> +u64 vidtv_extract_bits(u64 value, u8 start_bit, u8 nbits);
> +
>  #endif // VIDTV_COMMON_H
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_pes.c b/drivers/media/test-drivers/vidtv/vidtv_pes.c
> new file mode 100644
> index 0000000000000..bc631bac07778
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_pes.c
> @@ -0,0 +1,429 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Vidtv serves as a reference DVB driver and helps validate the existing APIs
> + * in the media subsystem. It can also aid developers working on userspace
> + * applications.
> + *
> + * This file contains the logic to translate the ES data for one access unit
> + * from an encoder into MPEG TS packets. It does so by first encapsulating it
> + * with a PES header and then splitting it into TS packets.
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> + */
> +
> +#include <linux/types.h>
> +#include <linux/printk.h>
> +#include "vidtv_pes.h"
> +#include "vidtv_common.h"
> +#include "vidtv_ts.h"
> +
> +#define PRIVATE_STREAM_1_ID 0xbd /* private_stream_1. See SMPTE 302M-2007 p.6 */
> +#define PES_HEADER_MAX_STUFFING_BYTES 32
> +#define PES_TS_HEADER_MAX_STUFFING_BYTES 182
> +
> +static u32 vidtv_pes_op_get_regular_len(bool send_pts, bool send_dts)
> +{
> +	u32 len = 0;
> +
> +	/* the flags must always be sent */
> +	len += sizeof(struct vidtv_pes_optional);
> +
> +	/* From all optionals, we might send these for now */
> +	if (send_pts && send_dts)
> +		len += sizeof(struct vidtv_pes_optional_pts_dts);
> +	else if (send_pts)
> +		len += sizeof(struct vidtv_pes_optional_pts);
> +
> +	return len;
> +}
> +
> +static u32 vidtv_pes_h_get_regular_len(bool send_pts, bool send_dts)
> +{
> +	/* PES header length notwithstanding stuffing bytes */
> +	u32 len = 0;
> +
> +	len += sizeof(struct vidtv_mpeg_pes);
> +	len += vidtv_pes_op_get_regular_len(send_pts, send_dts);
> +
> +	return len;
> +}
> +
> +static u32 vidtv_pes_write_header_stuffing(struct vidtv_mpeg_pes *pes_h,
> +					   struct pes_header_write_args args)
> +{
> +	/*
> +	 * This is a fixed 8-bit value equal to '1111 1111' that can be inserted
> +	 * by the encoder, for example to meet the requirements of the channel.
> +	 * It is discarded by the decoder. No more than 32 stuffing bytes shall
> +	 * be present in one PES packet header.
> +	 */
> +
> +	WARN_ON(args.n_pes_h_s_bytes > PES_HEADER_MAX_STUFFING_BYTES);

As commented, don't use WARN_ON(). At most, you could use WARN_ON_ONCE(),
as otherwise, you may end by causing serious performance issues if
the code starts to produce a flood of warnings at the dmesg.

I would use pr_warn_ratelimit() on all such cases.

> +
> +	if (args.n_pes_h_s_bytes > PES_HEADER_MAX_STUFFING_BYTES)
> +		args.n_pes_h_s_bytes = PES_HEADER_MAX_STUFFING_BYTES;
> +
> +	/* gives the length of the remainder of the PES header in bytes */
> +	pes_h->length += args.n_pes_h_s_bytes;
> +
> +	return vidtv_memset(args.dest_buf + args.dest_offset,
> +			    0xff,
> +			    args.n_pes_h_s_bytes,
> +			    args.dest_offset,
> +			    args.dest_buf_sz);
> +}
> +
> +static u32 vidtv_pes_write_pts_dts(struct pes_header_write_args args)
> +{
> +	u32 nbytes = 0;  /* the number of bytes written by this function */
> +
> +	struct vidtv_pes_optional_pts pts         = {0};
> +	struct vidtv_pes_optional_pts_dts pts_dts = {0};
> +	void   *op                                = NULL;
> +	size_t op_sz                              = 0;
> +
> +	if (!args.send_pts && args.send_dts)
> +		return 0;
> +
> +	/* see ISO/IEC 13818-1 : 2000 p. 32 */
> +
> +	if (args.send_pts && args.send_dts) {
> +		cpu_to_be64s(&args.pts);
> +		cpu_to_be64s(&args.dts);
> +		pts_dts.three = 0x3;
> +
> +		pts_dts.pts1    = vidtv_extract_bits(args.pts, 30, 3);
> +		pts_dts.marker1 = 0x1;
> +		pts_dts.pts2    = vidtv_extract_bits(args.pts, 15, 15);
> +		pts_dts.marker2 = 0x1;
> +		pts_dts.pts3    = vidtv_extract_bits(args.pts, 0, 15);
> +		pts_dts.marker3 = 0x1;
> +
> +		pts_dts.one = 0x1;
> +
> +		pts_dts.dts1    = vidtv_extract_bits(args.dts, 30, 3);
> +		pts_dts.marker1 = 0x1;
> +		pts_dts.dts2    = vidtv_extract_bits(args.dts, 15, 15);
> +		pts_dts.marker2 = 0x1;
> +		pts_dts.dts3    = vidtv_extract_bits(args.dts, 0, 15);
> +		pts_dts.marker3 = 0x1;
> +
> +		be64_to_cpus(&args.pts);
> +		be64_to_cpus(&args.dts);
> +
> +		op    = &pts_dts;
> +		op_sz = sizeof(pts_dts);
> +
> +	} else if (args.send_pts) {
> +		cpu_to_be64s(&args.pts);
> +		pts.two     = 0x2;
> +		pts.pts1    = vidtv_extract_bits(args.pts, 30, 3);
> +		pts.marker1 = 0x1;
> +		pts.pts2    = vidtv_extract_bits(args.pts, 15, 15);
> +		pts.marker2 = 0x1;
> +		pts.pts3    = vidtv_extract_bits(args.pts, 0, 15);
> +		pts.marker3 = 0x1;
> +		be64_to_cpus(&args.pts);
> +
> +		op    = &pts;
> +		op_sz = sizeof(pts);
> +	}
> +
> +	/* copy PTS/DTS optional */
> +	nbytes += vidtv_memcpy(args.dest_buf + args.dest_offset + nbytes,
> +			       op,
> +			       op_sz,
> +			       args.dest_offset + nbytes,
> +			       args.dest_buf_sz);
> +
> +	return nbytes;
> +}
> +
> +static u32 vidtv_pes_write_h(struct pes_header_write_args args)
> +{
> +	u32 nbytes = 0;  /* the number of bytes written by this function */
> +
> +	struct vidtv_mpeg_pes pes_header          = {0};
> +	struct vidtv_pes_optional pes_optional    = {0};
> +	struct pes_header_write_args pts_dts_args = args;
> +
> +	pes_header.packet_start_code_prefix = PES_START_CODE_PREFIX;
> +
> +	pes_header.stream_id = (args.is_s302m_pkt) ?
> +				PRIVATE_STREAM_1_ID :
> +				args.stream_id;
> +
> +	pes_header.length = vidtv_pes_op_get_regular_len(args.send_pts,
> +							 args.send_dts);
> +
> +	pes_optional.two     = 0x2;
> +
> +	pes_optional.PTS_DTS = (args.send_pts && args.send_dts) ?
> +			       0x3 :
> +			       (args.send_pts) ?
> +			       0x2 :
> +			       0x0;
> +
> +	/* copy header */
> +	cpu_to_be32s(&pes_header.bitfield);
> +	cpu_to_be16s(&pes_header.length);
> +
> +	nbytes += vidtv_memcpy(args.dest_buf + args.dest_offset + nbytes,
> +			       &pes_header,
> +			       sizeof(pes_header),
> +			       args.dest_offset + nbytes,
> +			       args.dest_buf_sz);
> +
> +	be32_to_cpus(&pes_header.bitfield);
> +	be16_to_cpus(&pes_header.length);

I don't like the idea of changing the "from" buffer endiannes, copy
and then restore it back to the original state. Is this really needed?

I would, instead, define:

	struct pes_header {
	...
		__be32 bitfield;
		__be16 length;
	...
	};

Then wherever you would touch them:

	u32 bitfield;
	u16 len;

	/* Write into BE fields */
	pes_header.bitfield = cpu_to_be32(bitfield);
	pes_header.length = cpu_to_be16(len);

	/* Read from BE fields */
	bitfield = be32_to_cpu(pes_header.bitfield);
	len = be16_to_cpu(pes_header.length);


As a side effect, when you use "__be16" and "__be32" types, gcc
and smatch/sparse will warn you if you mess with endiannes.

Same applies to similar code elsewhere.

> +
> +	/* copy optional header */
> +	cpu_to_be16s(&pes_optional.bitfield);
> +
> +	nbytes += vidtv_memcpy(args.dest_buf + args.dest_offset + nbytes,
> +			       &pes_optional,
> +			       sizeof(pes_optional),
> +			       args.dest_offset + nbytes,
> +			       args.dest_buf_sz);
> +
> +	be16_to_cpus(&pes_optional.bitfield);
> +
> +	pts_dts_args.dest_offset  = args.dest_offset + nbytes;
> +	nbytes                   += vidtv_pes_write_pts_dts(pts_dts_args);
> +
> +	/* write any PES header stuffing */
> +	nbytes += vidtv_pes_write_header_stuffing(&pes_header, args);
> +
> +	return nbytes;
> +}
> +
> +static u32 vidtv_pes_write_stuffing(struct vidtv_mpeg_ts *ts_h,
> +				    void *dest_buf,
> +				    u32 dest_offset,
> +				    u32 n_stuffing_bytes,
> +				    u32 buf_sz)
> +{
> +	/*
> +	 * For Transport Stream packets carrying PES packets, stuffing is
> +	 * needed when there is insufficient PES packet data to completely
> +	 * fill the Transport Stream packet payload bytes. Stuffing is
> +	 * accomplished by defining an adaptation field longer than the sum of
> +	 * the lengths of the data elements in it, so that the payload bytes
> +	 * remaining after the adaptation field exactly accommodates the
> +	 * available PES packet data. The extra space in the adaptation field
> +	 * is filled with stuffing bytes.
> +	 *
> +	 */
> +
> +	/* the number of bytes written by this function */
> +	u32    nbytes                         = 0;
> +	struct vidtv_mpeg_ts_adaption ts_adap = {0};
> +
> +	if (!n_stuffing_bytes)
> +		return nbytes;
> +
> +	ts_h->adaptation_field = 1;
> +
> +	WARN_ON(n_stuffing_bytes > PES_TS_HEADER_MAX_STUFFING_BYTES);
> +
> +	if (n_stuffing_bytes > PES_TS_HEADER_MAX_STUFFING_BYTES)
> +		n_stuffing_bytes = PES_TS_HEADER_MAX_STUFFING_BYTES;
> +
> +	/* the AF will only be its 'length' field with a value of zero */
> +	if (n_stuffing_bytes == 1) {
> +		nbytes += vidtv_memset(dest_buf + dest_offset + nbytes,
> +				       0,
> +				       n_stuffing_bytes,
> +				       dest_offset + nbytes,
> +				       buf_sz);
> +
> +		return nbytes;
> +	}
> +
> +	n_stuffing_bytes -= sizeof(ts_adap);
> +
> +	/* length _immediately_ following 'adaptation_field_length' */
> +	ts_adap.length = sizeof(ts_adap) -
> +			 sizeof(ts_adap.length) +
> +			 n_stuffing_bytes;
> +
> +	/* write the adap after the TS header */
> +	nbytes += vidtv_memcpy(dest_buf + dest_offset + nbytes,
> +			       &ts_adap,
> +			       sizeof(ts_adap),
> +			       dest_offset + nbytes,
> +			       buf_sz);
> +
> +	/* write the stuffing bytes */
> +	nbytes += vidtv_memset(dest_buf + dest_offset + nbytes,
> +			       0xff,
> +			       n_stuffing_bytes,
> +			       dest_offset + nbytes,
> +			       buf_sz);
> +
> +	return nbytes;
> +}
> +
> +static u32 vidtv_pes_write_ts_h(struct pes_ts_header_write_args args)
> +{
> +	/* number of bytes written by this function */
> +	u32    nbytes                  = 0;
> +	struct vidtv_mpeg_ts ts_header = {0};
> +
> +	ts_header.sync_byte        = TS_SYNC_BYTE;
> +	ts_header.tei              = 0;
> +	ts_header.pid              = args.pid;
> +	ts_header.priority         = 0;
> +	ts_header.scrambling       = 0;             /* not scrambled */
> +	ts_header.adaptation_field = 0;
> +	ts_header.payload          = 1;
> +
> +	ts_header.payload_start      = (!args.wrote_pes_header) ? 1 : 0;
> +	ts_header.continuity_counter = *args.continuity_counter;
> +
> +	vidtv_ts_inc_cc(args.continuity_counter);
> +
> +	cpu_to_be16s(&ts_header.bitfield);
> +
> +	/* write the TS header */
> +	nbytes += vidtv_memcpy(args.dest_buf + args.dest_offset + nbytes,
> +			       &ts_header,
> +			       sizeof(ts_header),
> +			       args.dest_offset + nbytes,
> +			       args.dest_buf_sz);
> +
> +	be16_to_cpus(&ts_header.bitfield);
> +	/* write stuffing, if any */
> +	nbytes += vidtv_pes_write_stuffing(&ts_header,
> +					   args.dest_buf,
> +					   args.dest_offset + nbytes,
> +					   args.n_stuffing_bytes,
> +					   args.dest_buf_sz);
> +
> +	return nbytes;
> +}
> +
> +u32 vidtv_pes_write_into(struct pes_write_args args)
> +{
> +	u32 nbytes_past_boundary = (args.dest_offset % TS_PACKET_LEN);
> +	bool aligned = (nbytes_past_boundary == 0);
> +
> +	struct pes_ts_header_write_args ts_header_args = {0};
> +	struct pes_header_write_args pes_header_args   = {0};
> +
> +	/* number of bytes written by this function */
> +	u32 nbytes        = 0;
> +	u32 remaining_len = args.access_unit_len;
> +
> +	bool wrote_pes_header = false;
> +	bool stuff            = false;
> +
> +	u32 available_space    = 0;
> +	u32 payload_write_len  = 0;
> +	u32 num_stuffing_bytes = 0;
> +
> +	/* Just a sanity check, should not really happen because we stuff the
> +	 * TS packet when we finish writing the PES data, but if this happens
> +	 * then we have messed up the logic somewhere.
> +	 *
> +	 * Also note that, unlike packets for PSI data, we need to carry PES
> +	 * packets aligned with the payload of transport packets, that is the
> +	 * first byte of each PES header must be the first byte in the payload
> +	 * of a transport packet. As a consequence, the last byte of a PES
> +	 * packet must be the last byte of the payload of a transport packet.
> +	 */
> +	WARN_ON(!aligned);

Same note as on a previous patch: if not aligned, you should re-align.

> +
> +	if (args.send_dts && !args.send_pts) {
> +		pr_warn("%s: forbidden value '01' for PTS_DTS flags", __func__);
> +		args.send_pts = true;
> +		args.pts      = args.dts;
> +	}
> +
> +	/* see SMPTE 302M clause 6.4 */
> +	if (args.is_s302m_pkt) {
> +		args.send_dts = false;
> +		args.send_pts = true;
> +	}
> +
> +	while (remaining_len) {
> +		/*
> +		 * The amount of space initially available in the TS packet.
> +		 * if this is the beginning of the PES packet, we need to
> +		 * take into account the space needed for the TS header _and_
> +		 * for the PES header
> +		 */
> +		available_space = (!wrote_pes_header) ?
> +				  TS_PAYLOAD_LEN -
> +				  vidtv_pes_h_get_regular_len(args.send_pts,
> +							      args.send_dts) :
> +				  TS_PAYLOAD_LEN;
> +
> +		/* if the encoder has inserted stuffing bytes in the PES
> +		 * header, account for them.
> +		 */
> +		available_space -= args.n_pes_h_s_bytes;
> +
> +		/* whether we need to stuff the TS packet to align the buffer */
> +		stuff = remaining_len < available_space;
> +
> +		/*
> +		 * how much of the _actual_ payload we should write in this
> +		 * packet.
> +		 */
> +		payload_write_len = (stuff) ?
> +				    remaining_len :
> +				    available_space;
> +
> +		num_stuffing_bytes = available_space - payload_write_len;
> +
> +		/* write ts header */
> +		ts_header_args.dest_buf           = args.dest_buf;
> +		ts_header_args.dest_offset        = args.dest_offset + nbytes;
> +		ts_header_args.dest_buf_sz        = args.dest_buf_sz;
> +		ts_header_args.pid                = args.pid;
> +		ts_header_args.continuity_counter = args.continuity_counter;
> +		ts_header_args.wrote_pes_header   = wrote_pes_header;
> +		ts_header_args.n_stuffing_bytes   = num_stuffing_bytes;
> +
> +		nbytes += vidtv_pes_write_ts_h(ts_header_args);
> +
> +		if (!wrote_pes_header) {
> +			/* write the PES header only once */
> +			pes_header_args.dest_buf        = args.dest_buf;
> +
> +			pes_header_args.dest_offset     = args.dest_offset +
> +							  nbytes;
> +
> +			pes_header_args.dest_buf_sz     = args.dest_buf_sz;
> +			pes_header_args.is_s302m_pkt    = args.is_s302m_pkt;
> +			pes_header_args.send_pts        = args.send_pts;
> +			pes_header_args.pts             = args.pts;
> +			pes_header_args.send_dts        = args.send_dts;
> +			pes_header_args.dts             = args.dts;
> +			pes_header_args.stream_id       = args.stream_id;
> +			pes_header_args.n_pes_h_s_bytes = args.n_pes_h_s_bytes;
> +
> +			nbytes           += vidtv_pes_write_h(pes_header_args);
> +			wrote_pes_header  = true;
> +		}
> +
> +		/* write as much of the payload as we possibly can */
> +		nbytes += vidtv_memcpy(args.dest_buf +
> +				       args.dest_offset +
> +				       nbytes,
> +				       args.from,
> +				       payload_write_len,
> +				       args.dest_offset + nbytes,
> +				       args.dest_buf_sz);
> +
> +		args.from        += payload_write_len;
> +		args.dest_offset += nbytes;
> +
> +		/* sanity check for underflow */
> +		WARN_ON(remaining_len - payload_write_len > remaining_len);
> +		remaining_len -= payload_write_len;
> +	}
> +
> +	return nbytes;
> +}
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_pes.h b/drivers/media/test-drivers/vidtv/vidtv_pes.h
> new file mode 100644
> index 0000000000000..00ede32adf476
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_pes.h
> @@ -0,0 +1,185 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Vidtv serves as a reference DVB driver and helps validate the existing APIs
> + * in the media subsystem. It can also aid developers working on userspace
> + * applications.
> + *
> + * This file contains the logic to translate the ES data for one access unit
> + * from an encoder into MPEG TS packets. It does so by first encapsulating it
> + * with a PES header and then splitting it into TS packets.
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> + */
> +
> +#ifndef VIDTV_PES_H
> +#define VIDTV_PES_H
> +
> +#include <asm/byteorder.h>
> +#include <linux/types.h>
> +#include "vidtv_common.h"
> +
> +#define PES_MAX_LEN 65536 /* Set 'length' to 0 if greater */
> +#define PES_START_CODE_PREFIX 0x001 /* 00 00 01 */
> +
> +struct vidtv_pes_optional_pts {
> +	struct {
> +	#if defined(__LITTLE_ENDIAN_BITFIELD)
> +		u8 marker3:1; /* always 0x1 */
> +		u16 pts3:15;
> +		u8 marker2:1; /* always 0x1 */
> +		u16 pts2:15;
> +		u8 marker1:1; /* always 0x1 */
> +		u8 pts1:3;
> +		u8 two:4; /* always 0010b */
> +	#elif defined(__BIG_ENDIAN_BITFIELD)
> +		u8 two:4; /* always 0010b */
> +		u8 pts1:3;
> +		u8 marker1:1; /* always 0x1 */
> +		u16 pts2:15;
> +		u8 marker2:1; /* always 0x1 */
> +		u16 pts3:15;
> +		u8 marker3:1; /* always 0x1 */
> +	#else
> +	#error  "Please fix <asm/byteorder.h>"
> +	#endif
> +	} __packed;
> +} __packed;
> +
> +struct vidtv_pes_optional_pts_dts {
> +	struct {
> +	#if defined(__LITTLE_ENDIAN_BITFIELD)
> +		u8 marker6:1; /* always 0x1 */
> +		u16 dts3:15;
> +		u8 marker5:1; /* always 0x1 */
> +		u16 dts2:15;
> +		u8 marker4:1; /* always 0x1 */
> +		u8 dts1:3;
> +		u8 one:4; /* always 0001b */
> +		u8 marker3:1; /* always 0x1 */
> +		u16 pts3:15;
> +		u8 marker2:1; /* always 0x1 */
> +		u16 pts2:15;
> +		u8 marker1:1; /* always 0x1 */
> +		u8 pts1:3;
> +		u8 three:4; /* always 0011b */
> +	#elif defined(__BIG_ENDIAN_BITFIELD)
> +		u8 three:4; /* always 0011b */
> +		u8 pts1:3;
> +		u8 marker1:1; /* always 0x1 */
> +		u16 pts2:15;
> +		u8 marker2:1; /* always 0x1 */
> +		u16 pts3:15;
> +		u8 marker3:1; /* always 0x1 */
> +		u8 one:4; /* always 0001b */
> +		u8 dts1:3;
> +		u8 marker4:1; /* always 0x1 */
> +		u16 dts2:15;
> +		u8 marker5:1; /* always 0x1 */
> +		u16 dts3:15;
> +		u8 marker6:1; /* always 0x1 */
> +	#else
> +	#error  "Please fix <asm/byteorder.h>"
> +	#endif
> +	} __packed;
> +} __packed;
> +
> +struct vidtv_pes_optional {
> +	union {
> +		u16 bitfield;
> +		struct {
> +			u16 two:2; /* always 0x2*/
> +			u16 PES_scrambling_control:2;
> +			u16 PES_priority:1;
> +			u16 data_alignment_indicator:1; /* ununsed for us */
> +			u16 copyright:1;
> +			u16 original_or_copy:1;
> +			u16 PTS_DTS:2;
> +			/* These flags show which components are actually
> +			 * present in the "optinal fields" in the optinal PES
> +			 * header and which are not. Vidtv currently does
> +			 * not need any of these.
> +			 */
> +			u16 ESCR:1;
> +			u16 ES_rate:1;
> +			u16 DSM_trick_mode:1;
> +			u16 additional_copy_info:1;
> +			u16 PES_CRC:1;
> +			u16 PES_extension:1;
> +		} __packed;
> +	} __packed;
> +	u8 length;
> +} __packed;
> +
> +struct vidtv_mpeg_pes {
> +	union {
> +		u32 bitfield;
> +		struct {
> +			/* These two together make the 32-bit start-code */
> +			u32  packet_start_code_prefix:24;
> +			u32  stream_id:8;
> +		} __packed;
> +	} __packed;
> +	/* after this field until the end of the PES data payload */
> +	u16 length;
> +	struct vidtv_pes_optional optional[];
> +} __packed;
> +
> +struct pes_header_write_args {
> +	void *dest_buf;
> +	u32 dest_offset;
> +	u32 dest_buf_sz;
> +	bool is_s302m_pkt;
> +
> +	bool send_pts;
> +	u64 pts;
> +
> +	bool send_dts;
> +	u64 dts;
> +
> +	u16 stream_id;
> +	/* might be used by an encoder if needed, gets discarded by decoder */
> +	u32 n_pes_h_s_bytes;
> +};
> +
> +struct pes_ts_header_write_args {
> +	void *dest_buf;
> +	u32 dest_offset;
> +	u32 dest_buf_sz;
> +	u16 pid;
> +	u8 *continuity_counter;
> +	bool wrote_pes_header;
> +	u32 n_stuffing_bytes;
> +};
> +
> +struct pes_write_args {
> +	void *dest_buf; /* pointer to a program mux buffer */
> +	void *from; /* pointer to the encoder buffer */
> +
> +	/* the size of one access unit (with any headers it might need) */
> +	u32 access_unit_len;
> +
> +	u32 dest_offset; /* where to start writing in the program mux buffer */
> +	u32 dest_buf_sz; /* how big is the program mux buffer */
> +	u16 pid; /* TS packet ID */
> +
> +	/* use SMPTE 302M to packetize the data */
> +	bool is_s302m_pkt;
> +
> +	u8 *continuity_counter; /* incremented for every TS packet */
> +
> +	/* Examples: Audio streams (0xc0-0xdf), Video streams (0xe0-0xef) */
> +	u16 stream_id;
> +
> +	bool send_pts;
> +	u64 pts;
> +
> +	bool send_dts;
> +	u64 dts;
> +
> +	/* might be used by an encoder if needed, gets discarded by decoder */
> +	u32 n_pes_h_s_bytes;
> +};
> +
> +u32 vidtv_pes_write_into(struct pes_write_args args);
> +
> +#endif // VIDTV_PES_H



Thanks,
Mauro