[FFmpeg-devel] [PATCH] Demuxer for Leitch/Harris' VR native stream format (LXF)
Michael Niedermayer
michaelni
Sat Sep 25 05:22:51 CEST 2010
On Wed, Sep 15, 2010 at 03:16:44PM +0200, Tomas H?rdin wrote:
> On Mon, 2010-09-13 at 22:06 +0200, Michael Niedermayer wrote:
> > On Mon, Sep 13, 2010 at 08:44:00PM +0100, M?ns Rullg?rd wrote:
> > > Michael Niedermayer <michaelni at gmx.at> writes:
> > >
> > > > On Mon, Sep 13, 2010 at 10:56:43AM +0100, M?ns Rullg?rd wrote:
> > > >> Tomas H?rdin <tomas.hardin at codemill.se> writes:
> > > > [...]
> > > >> >> > +//reads and checksums packet header. returns format and size of payload
> > > >> >> > +static int get_packet_header(AVFormatContext *s, unsigned char *header,
> > > >> >> > + uint32_t *format)
> > > >> >> > +{
> > > >> >> > + LXFDemuxContext *lxf = s->priv_data;
> > > >> >> > + ByteIOContext *pb = s->pb;
> > > >> >> > + int size, track_size, samples;
> > > >> >> > + AVStream *st;
> > > >> >> > +
> > > >> >> > + if (get_buffer(pb, header, LXF_PACKET_HEADER_SIZE) != LXF_PACKET_HEADER_SIZE)
> > > >> >> > + return AVERROR(EIO);
> > > >> >> > +
> > > >> >> > + if (memcmp(header, LXF_IDENT, LXF_IDENT_LENGTH)) {
> > > >> >> > + av_log(s, AV_LOG_ERROR, "packet ident mismatch - out of sync?\n");
> > > >> >> > + return -1;
> > > >> >> > + }
> > > >> >> > +
> > > >> >> > + if (check_checksum(header))
> > > >> >> > + av_log(s, AV_LOG_ERROR, "checksum error\n");
> > > >> >> > +
> > > >> >> > + *format = AV_RL32(&header[32]);
> > > >> >> > + size = AV_RL32(&header[36]);
> > > >> >> > +
> > > >> >> > + //type
> > > >> >> > + switch (AV_RL32(&header[16])) {
> > > >> >> > + case 0:
> > > >> >> > + //video
> > > >> >> > + //skip VBI data and metadata
> > > >> >> > + url_fskip(pb, AV_RL32(&header[44]) + AV_RL32(&header[52]));
> > > >> >>
> > > >> >> cant this lead to a backward seek and thus infinite loop ?
> > > >> >
> > > >> > Yes, assuming AV_RL32() returns signed. Fixed by casting to uint32_t and
> > > >> > splitting up into two skips.
> > > >
> > > > split is ugly
> > > >
> > > >>
> > > >> AV_RL32() returns an unsigned value.
> > > >
> > > > maybe it should but i dont think it does
> > > >
> > > > # define AV_RL32(x) \
> > > > ((((const uint8_t*)(x))[3] << 24) | \
> > > > (((const uint8_t*)(x))[2] << 16) | \
> > > > (((const uint8_t*)(x))[1] << 8) | \
> > > > ((const uint8_t*)(x))[0])
> > >
> > > You are right. Should we change it?
> >
> > i do not know, but at least we should make sure all implementations of AV_R*
> > are consistent in terms of signedness
>
> I went with a double cast to eliminate the split seek and guarantee that
> they are added together correctly.
>
> I decided to give the CODEC_ID_PCM_LXF idea a try. Two patches attached:
> one adds a new PCM decoder called "pcm_lxf", which performs both
> unpacking and de-planerization. The other patch is a demuxer that makes
> use of this decoder, which made the code a bit simpler.
>
> I also cleaned up the code a bit more, especially regarding handling the
> four supported bit depths. It also makes use of av_popcount() now.
>
> /Tomas
> Changelog | 1
> doc/general.texi | 2
> libavformat/Makefile | 1
> libavformat/allformats.c | 1
> libavformat/avformat.h | 4
> libavformat/lxfdec.c | 320 +++++++++++++++++++++++++++++++++++++++++++++++
> 6 files changed, 327 insertions(+), 2 deletions(-)
> 3ddced6788bd3a2f817c816d18e0c682347e7834 lxfdec5.patch
> diff --git a/Changelog b/Changelog
> index 503ac43..d7d012c 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -36,6 +36,7 @@ version <next>:
> - G.722 ADPCM audio decoder
> - R10k video decoder
> - ocv_smooth filter
> +- Demuxer for Leitch/Harris' VR native stream format (LXF)
>
>
> version 0.6:
> diff --git a/doc/general.texi b/doc/general.texi
> index 9a3200f..3cb1eea 100644
> --- a/doc/general.texi
> +++ b/doc/general.texi
> @@ -114,6 +114,8 @@ library:
> @tab A format used by libvpx
> @item LMLM4 @tab @tab X
> @tab Used by Linux Media Labs MPEG-4 PCI boards
> + at item LXF @tab @tab X
> + @tab VR native stream format, used by Leitch/Harris' video servers.
> @item Matroska @tab X @tab X
> @item Matroska audio @tab X @tab
> @item MAXIS XA @tab @tab X
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 50ff5de..dfeede7 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -105,6 +105,7 @@ OBJS-$(CONFIG_ISS_DEMUXER) += iss.o
> OBJS-$(CONFIG_IV8_DEMUXER) += iv8.o
> OBJS-$(CONFIG_IVF_DEMUXER) += ivfdec.o riff.o
> OBJS-$(CONFIG_LMLM4_DEMUXER) += lmlm4.o
> +OBJS-$(CONFIG_LXF_DEMUXER) += lxfdec.o
> OBJS-$(CONFIG_M4V_DEMUXER) += m4vdec.o rawdec.o
> OBJS-$(CONFIG_M4V_MUXER) += rawenc.o
> OBJS-$(CONFIG_MATROSKA_DEMUXER) += matroskadec.o matroska.o \
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index f9407f0..f9e1fb3 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -110,6 +110,7 @@ void av_register_all(void)
> REGISTER_DEMUXER (IV8, iv8);
> REGISTER_DEMUXER (IVF, ivf);
> REGISTER_DEMUXER (LMLM4, lmlm4);
> + REGISTER_DEMUXER (LXF, lxf);
> REGISTER_MUXDEMUX (M4V, m4v);
> REGISTER_MUXER (MD5, md5);
> REGISTER_MUXDEMUX (MATROSKA, matroska);
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index 0520530..362a056 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -22,8 +22,8 @@
> #define AVFORMAT_AVFORMAT_H
>
> #define LIBAVFORMAT_VERSION_MAJOR 52
> -#define LIBAVFORMAT_VERSION_MINOR 78
> -#define LIBAVFORMAT_VERSION_MICRO 5
> +#define LIBAVFORMAT_VERSION_MINOR 79
> +#define LIBAVFORMAT_VERSION_MICRO 0
>
> #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
> LIBAVFORMAT_VERSION_MINOR, \
> diff --git a/libavformat/lxfdec.c b/libavformat/lxfdec.c
> new file mode 100644
> index 0000000..3667b69
> --- /dev/null
> +++ b/libavformat/lxfdec.c
> @@ -0,0 +1,320 @@
> +/*
> + * LXF demuxer
> + * Copyright (c) 2010 Tomas H?rdin
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg 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.
> + *
> + * FFmpeg 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 FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#include "libavutil/intreadwrite.h"
> +#include "avformat.h"
> +#include "riff.h"
> +
> +#define LXF_PACKET_HEADER_SIZE 60
> +#define LXF_HEADER_DATA_SIZE 120
> +#define LXF_IDENT "LEITCH\0"
> +#define LXF_IDENT_LENGTH 8
> +#define LXF_SAMPLERATE 48000
> +#define LXF_MAX_AUDIO_PACKET (8008*15*4) //15-channel 32-bit NTSC audio frame
> +
> +static const AVCodecTag lxf_tags[] = {
> + { CODEC_ID_MJPEG, 0 },
> + { CODEC_ID_MPEG1VIDEO, 1 },
> + { CODEC_ID_MPEG2VIDEO, 2 }, //MpMl, 4:2:0
> + { CODEC_ID_MPEG2VIDEO, 3 }, //MpPl, 4:2:2
> + { CODEC_ID_DVVIDEO, 4 }, //DV25
> + { CODEC_ID_DVVIDEO, 5 }, //DVCPRO
> + { CODEC_ID_DVVIDEO, 6 }, //DVCPRO50
> + { CODEC_ID_RAWVIDEO, 7 }, //PIX_FMT_ARGB, where alpha is used for chroma keying
> + { CODEC_ID_RAWVIDEO, 8 }, //16-bit chroma key
> + { CODEC_ID_MPEG2VIDEO, 9 }, //4:2:2 CBP ("Constrained Bytes per Gop")
> + { CODEC_ID_NONE, 0 },
> +};
> +
> +typedef struct {
> + int channels; //number of audio channels. 0 -> no audio
> + uint8_t temp[LXF_MAX_AUDIO_PACKET]; //temp buffer for de-planarizing the audio data
> + int frame_number;
> +} LXFDemuxContext;
> +
> +static int lxf_probe(AVProbeData *p)
> +{
> + if (!memcmp(p->buf, LXF_IDENT, LXF_IDENT_LENGTH))
> + return AVPROBE_SCORE_MAX;
> +
> + return 0;
> +}
> +
> +/**
> + * Verify the checksum of an LXF packet header
> + *
> + * @param[in] header the packet header to check
> + * @return zero if the checksum is OK, non-zero otherwise
> + */
> +static int check_checksum(const uint8_t *header)
> +{
> + int x;
> + uint32_t sum = 0;
> +
> + for (x = 0; x < LXF_PACKET_HEADER_SIZE; x += 4)
> + sum += AV_RL32(&header[x]);
> +
> + return sum;
> +}
> +
> +/**
> + * Read and checksum the next packet header
> + *
> + * @param[out] header the read packet header
> + * @param[out] format context dependent format information
> + * @return the size of the payload following the header or < 0 on failure
> + */
> +static int get_packet_header(AVFormatContext *s, uint8_t *header, uint32_t *format)
> +{
> + ByteIOContext *pb = s->pb;
> + int size, track_size, samples;
> + AVStream *st;
> +
> + if (get_buffer(pb, header, LXF_PACKET_HEADER_SIZE) != LXF_PACKET_HEADER_SIZE)
> + return AVERROR(EIO);
> +
> + if (memcmp(header, LXF_IDENT, LXF_IDENT_LENGTH)) {
> + av_log(s, AV_LOG_ERROR, "packet ident mismatch - out of sync?\n");
> + return -1;
> + }
searching for the next matching ident instead of failing would make sense
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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