Re: [FFmpeg-devel] [PATCH] avformat: add bitpacked demuxer

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

lance.lmwang@gmail.com:
> On Tue, Dec 21, 2021 at 02:20:31PM +0100, Andreas Rheinhardt wrote:
>> lance.lmwang@gmail.com:
>>> From: Limin Wang <lance.lmwang@gmail.com>
>>>
>>> Allows user can playback bitpacked pixel format directly:
>>> ffplay -video_size 1280x720 test.bitpacked
>>> ffplay -f bitpacked -video_size 1280x720 -pixel_format uyvy422 test.yuv
>>>
>>> Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
>>> ---
>>>  libavformat/Makefile       |   1 +
>>>  libavformat/allformats.c   |   1 +
>>>  libavformat/bitpackeddec.c | 136 +++++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 138 insertions(+)
>>>  create mode 100644 libavformat/bitpackeddec.c
>>>
>>> diff --git a/libavformat/Makefile b/libavformat/Makefile
>>> index 2b5caf9..90b7333 100644
>>> --- a/libavformat/Makefile
>>> +++ b/libavformat/Makefile
>>> @@ -138,6 +138,7 @@ OBJS-$(CONFIG_BINKA_DEMUXER)             += binka.o
>>>  OBJS-$(CONFIG_BINTEXT_DEMUXER)           += bintext.o sauce.o
>>>  OBJS-$(CONFIG_BIT_DEMUXER)               += bit.o
>>>  OBJS-$(CONFIG_BIT_MUXER)                 += bit.o
>>> +OBJS-$(CONFIG_BITPACKED_DEMUXER)         += bitpackeddec.o
>>>  OBJS-$(CONFIG_BMV_DEMUXER)               += bmv.o
>>>  OBJS-$(CONFIG_BOA_DEMUXER)               += boadec.o
>>>  OBJS-$(CONFIG_BFSTM_DEMUXER)             += brstm.o
>>> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
>>> index 1054ac9..a100639 100644
>>> --- a/libavformat/allformats.c
>>> +++ b/libavformat/allformats.c
>>> @@ -96,6 +96,7 @@ extern const AVInputFormat  ff_bink_demuxer;
>>>  extern const AVInputFormat  ff_binka_demuxer;
>>>  extern const AVInputFormat  ff_bit_demuxer;
>>>  extern const AVOutputFormat ff_bit_muxer;
>>> +extern const AVInputFormat  ff_bitpacked_demuxer;
>>>  extern const AVInputFormat  ff_bmv_demuxer;
>>>  extern const AVInputFormat  ff_bfstm_demuxer;
>>>  extern const AVInputFormat  ff_brstm_demuxer;
>>> diff --git a/libavformat/bitpackeddec.c b/libavformat/bitpackeddec.c
>>> new file mode 100644
>>> index 0000000..ba404ad
>>> --- /dev/null
>>> +++ b/libavformat/bitpackeddec.c
>>> @@ -0,0 +1,136 @@
>>> +/*
>>> + * Raw bitpacked video demuxer
>>> + * Copyright (c) 2021 Limin Wang
>>> + *
>>> + * 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/imgutils.h"
>>> +#include "libavutil/parseutils.h"
>>> +#include "libavutil/pixdesc.h"
>>> +#include "libavutil/opt.h"
>>> +#include "internal.h"
>>> +#include "avformat.h"
>>> +
>>> +typedef struct BitPackedDemuxerContext {
>>> +    const AVClass *class;     /**< Class for private options. */
>>> +    int width, height;        /**< Integers describing video size, set by a private option. */
>>> +    char *pixel_format;       /**< Set by a private option. */
>>> +    AVRational framerate;     /**< AVRational describing framerate, set by a private option. */
>>> +} BitPackedDemuxerContext;
>>> +
>>> +static int bitpacked_read_header(AVFormatContext *ctx)
>>> +{
>>> +    BitPackedDemuxerContext *s = ctx->priv_data;
>>> +    AVStream *st;
>>> +    enum AVPixelFormat pix_fmt;
>>> +    unsigned int pgroup; /* size of the pixel group in bytes */
>>> +    unsigned int xinc;
>>> +    const AVPixFmtDescriptor *desc;
>>> +    int tag;
>>> +    int ret;
>>> +
>>> +    st = avformat_new_stream(ctx, NULL);
>>> +    if (!st)
>>> +        return AVERROR(ENOMEM);
>>> +
>>> +    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
>>> +    st->codecpar->codec_id = ctx->iformat->raw_codec_id;
>>
>> Seems like you copied this code from somewhere. Where did you copy it from?
> 
> Yes, this part is coming from v210 demuxer I think. 
> 

The original source seems to be rawvideodec; it has exactly the same
options, exactly the same private struct, exactly the same read_packet
function and its read_header function is quite similar. You should reuse
the common code.

>>
>>> +
>>> +    if ((pix_fmt = av_get_pix_fmt(s->pixel_format)) == AV_PIX_FMT_NONE) {
>>> +        av_log(ctx, AV_LOG_ERROR, "No such pixel format: %s.\n", s->pixel_format);
>>> +        return AVERROR(EINVAL);
>>> +    }
>>> +    desc = av_pix_fmt_desc_get(pix_fmt);
>>> +
>>> +    ret = av_image_check_size(s->width, s->height, 0, ctx);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    st->codecpar->width    = s->width;
>>> +    st->codecpar->height   = s->height;
>>> +    st->codecpar->format   = pix_fmt;
>>> +    st->codecpar->bits_per_coded_sample = av_get_bits_per_pixel(desc);
>>> +
>>> +    if (pix_fmt  == AV_PIX_FMT_YUV422P10) {
>>> +        tag = MKTAG('U', 'Y', 'V', 'Y');
>>> +        pgroup = 5;
>>> +        xinc   = 2;
>>> +    } else if (pix_fmt  == AV_PIX_FMT_UYVY422) {
>>> +        tag = MKTAG('U', 'Y', 'V', 'Y');
>>> +        pgroup = 4;
>>> +        xinc   = 2;
>>> +        pix_fmt = AV_PIX_FMT_UYVY422;
>>> +        st->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
>>> +    } else {
>>> +        av_log(ctx, AV_LOG_ERROR, "unsupported the pixel format: %s yet.\n",
>>> +               s->pixel_format);
>>> +        return AVERROR(EINVAL);
>>> +    }
>>> +    st->codecpar->format   = pix_fmt;
>>> +    st->codecpar->codec_tag = tag;
>>> +
>>> +    avpriv_set_pts_info(st, 64, s->framerate.den, s->framerate.num);
>>> +    ctx->packet_size  = s->width * s->height * pgroup / xinc;
>>> +    st->codecpar->bit_rate = av_rescale_q(ctx->packet_size,
>>> +                                         (AVRational){8,1}, st->time_base);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int bitpacked_read_packet(AVFormatContext *s, AVPacket *pkt)
>>> +{
>>> +    int ret;
>>> +
>>> +    ret = av_get_packet(s->pb, pkt, s->packet_size);
>>> +    pkt->pts = pkt->dts = pkt->pos / s->packet_size;
>>> +
>>> +    pkt->stream_index = 0;
>>> +    if (ret < 0)
>>> +        return ret;
>>> +    return 0;
>>> +}
>>> +
>>> +#define OFFSET(x) offsetof(BitPackedDemuxerContext, x)
>>> +#define DEC AV_OPT_FLAG_DECODING_PARAM
>>> +static const AVOption bitpacked_options[] = {
>>> +    { "video_size", "set frame size", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, DEC },
>>> +    { "pixel_format", "set pixel format", OFFSET(pixel_format), AV_OPT_TYPE_STRING, {.str = "yuv422p10"}, 0, 0, DEC },
>>> +    { "framerate", "set frame rate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC },
>>> +    { NULL },
>>> +};
>>> +
>>> +static const AVClass bitpacked_demuxer_class = {
>>> +    .class_name = "bitpacked demuxer",
>>> +    .item_name  = av_default_item_name,
>>> +    .option     = bitpacked_options,
>>> +    .version    = LIBAVUTIL_VERSION_INT,
>>> +};
>>> +
>>> +#if CONFIG_BITPACKED_DEMUXER
>>> +const AVInputFormat ff_bitpacked_demuxer = {
>>> +    .name           = "bitpacked",
>>> +    .long_name      = NULL_IF_CONFIG_SMALL("Bitpacked"),
>>> +    .priv_data_size = sizeof(BitPackedDemuxerContext),
>>> +    .read_header    = bitpacked_read_header,
>>> +    .read_packet    = bitpacked_read_packet,
>>> +    .flags          = AVFMT_GENERIC_INDEX,
>>> +    .extensions     = "bitpacked",
>>> +    .raw_codec_id   = AV_CODEC_ID_BITPACKED,
>>> +    .priv_class     = &bitpacked_demuxer_class,
>>> +};
>>> +#endif // CONFIG_BITPACKED_DEMUXER
>>>

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