[FFmpeg-devel] [PATCH v3 1/2] codec: bitpacked: add decoder

Michael Niedermayer michael at niedermayer.cc
Wed Mar 1 00:10:23 EET 2017


On Tue, Feb 28, 2017 at 01:39:07PM -0500, Damien Riegel wrote:
> Add a codec capable of decoding some formats of the RFC4175. For now
> it's only capable of handling YCbCr-4:2:2 with 8-bit or 10-bit depth.
> 
> For 8-bit it's a simple pass-through, for 10-bit it depacks the stream
> in the AV_PIX_FMT_YUV422P10 pixel format.
> 
> Signed-off-by: Damien Riegel <damien.riegel at savoirfairelinux.com>
> ---
> Changes in v3:
>  - Codec has been renamed bitpacked (instead of vrawdepay)
>  - A decoding function is now chosen at codec init based on the pixel
>    format
>  - Codec marked as experimental
> 
>  libavcodec/Makefile     |   1 +
>  libavcodec/allcodecs.c  |   1 +
>  libavcodec/avcodec.h    |   1 +
>  libavcodec/bitpacked.c  | 148 ++++++++++++++++++++++++++++++++++++++++++++++++
>  libavcodec/codec_desc.c |   7 +++
>  5 files changed, 158 insertions(+)
>  create mode 100644 libavcodec/bitpacked.c
> 
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 1bea44ad91..dc5e684f10 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -214,6 +214,7 @@ OBJS-$(CONFIG_BINK_DECODER)            += bink.o binkdsp.o
>  OBJS-$(CONFIG_BINKAUDIO_DCT_DECODER)   += binkaudio.o
>  OBJS-$(CONFIG_BINKAUDIO_RDFT_DECODER)  += binkaudio.o
>  OBJS-$(CONFIG_BINTEXT_DECODER)         += bintext.o cga_data.o
> +OBJS-$(CONFIG_BITPACKED_DECODER)       += bitpacked.o
>  OBJS-$(CONFIG_BMP_DECODER)             += bmp.o msrledec.o
>  OBJS-$(CONFIG_BMP_ENCODER)             += bmpenc.o
>  OBJS-$(CONFIG_BMV_AUDIO_DECODER)       += bmvaudio.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index eee322b2b8..86a8fd56c5 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -366,6 +366,7 @@ void avcodec_register_all(void)
>      REGISTER_DECODER(VP8,               vp8);
>      REGISTER_DECODER(VP9,               vp9);
>      REGISTER_DECODER(VQA,               vqa);
> +    REGISTER_DECODER(BITPACKED,         bitpacked);
>      REGISTER_DECODER(WEBP,              webp);
>      REGISTER_ENCODER(WRAPPED_AVFRAME,   wrapped_avframe);
>      REGISTER_ENCDEC (WMV1,              wmv1);
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 925a8c7277..a0d07c64bc 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -416,6 +416,7 @@ enum AVCodecID {
>      AV_CODEC_ID_SPEEDHQ,
>      AV_CODEC_ID_FMVC,
>      AV_CODEC_ID_SCPR,
> +    AV_CODEC_ID_BITPACKED,
>  
>      /* various PCM "codecs" */
>      AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
> diff --git a/libavcodec/bitpacked.c b/libavcodec/bitpacked.c
> new file mode 100644
> index 0000000000..1d935b71a1
> --- /dev/null
> +++ b/libavcodec/bitpacked.c
> @@ -0,0 +1,148 @@
> +/*
> + * Unpack bit-packed streams to formats supported by FFmpeg
> + * Copyright (c) 2017 Savoir-faire Linux, Inc
> + *
> + * 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
> + */
> +
> +/* Development sponsored by CBC/Radio-Canada */
> +
> +/**
> + * @file
> + * Bitpacked
> + */
> +

> +#include <libavutil/imgutils.h>

wrong directory


> +#include "avcodec.h"
> +#include "internal.h"
> +#include "get_bits.h"
> +
> +struct BitpackedContext {
> +    int (*decode)(AVCodecContext *avctx, AVFrame *frame,
> +                  AVPacket *pkt);
> +};
> +

> +/* For this format, it's a simple passthrough */
> +static int bitpacked_decode_uyvy422(AVCodecContext *avctx, AVFrame *frame,
> +                                    AVPacket *avpkt)
> +{
> +    int ret;
> +
> +    /* there is no need to copy as the data already match
> +     * a known pixel format */
> +    frame->buf[0] = av_buffer_ref(avpkt->buf);
> +    ret = av_image_fill_arrays(frame->data, frame->linesize, avpkt->data,
> +                               avctx->pix_fmt, avctx->width, avctx->height, 1);

linesize and the initial data pointers have some alignment requirements

they may need to be checked before pass through


> +    if (ret < 0) {
> +        av_buffer_unref(&frame->buf[0]);
> +        return ret;
> +    }
> +
> +    return 0;
> +}
> +
> +static int bitpacked_decode_yuv422p10(AVCodecContext *avctx, AVFrame *frame,
> +                                      AVPacket *avpkt)
> +{
> +    GetBitContext bc;
> +    uint16_t *y, *u, *v;
> +    int ret, i;
> +
> +    ret = ff_get_buffer(avctx, frame, 0);
> +    if (ret < 0)
> +        return ret;
> +
> +    y = (uint16_t*)frame->data[0];
> +    u = (uint16_t*)frame->data[1];
> +    v = (uint16_t*)frame->data[2];
> +

> +    if (avctx->width * avctx->height * 20 > avpkt->size * 8)
> +        return AVERROR_INVALIDDATA;

this should use 64bit


> +
> +    ret = init_get_bits(&bc, avpkt->data, avctx->width * avctx->height * 20);
> +    if (ret)
> +        return ret;
> +

> +    for (i = 0; i < (avctx->width * avctx->height) / 2; i++) {
> +        *u++ = get_bits(&bc, 10);
> +        *y++ = get_bits(&bc, 10);
> +        *v++ = get_bits(&bc, 10);
> +        *y++ = get_bits(&bc, 10);

custom code to read this would likely be faster tha the generic
bit reader

also this looks wrong, there is no access to linesize
also is there a check for width to be even ? 


> +    }
> +
> +    return 0;
> +}
> +

> +static av_cold int bitpacked_init_decoder(AVCodecContext *avctx)
> +{
> +    struct BitpackedContext *bc = avctx->priv_data;
> +
> +    if (!avctx->codec_tag || !avctx->width || !avctx->height)
> +        return -1;
> +
> +    if (avctx->codec_tag == MKTAG('U', 'Y', 'V', 'Y')) {
> +        if (avctx->bits_per_coded_sample == 16 &&
> +            avctx->pix_fmt == AV_PIX_FMT_UYVY422)
> +            bc->decode = bitpacked_decode_uyvy422;
> +        else if (avctx->bits_per_coded_sample == 20 &&
> +                 avctx->pix_fmt == AV_PIX_FMT_YUV422P10)
> +            bc->decode = bitpacked_decode_yuv422p10;
> +        else
> +            return -1;
> +    } else {
> +        return -1;
> +    }

please use AVERROR... codes


> +
> +    return 0;
> +}
> +

> +static av_cold int bitpacked_close_decoder(AVCodecContext *avctx)
> +{
> +    return 0;
> +}

uneeded if it does nothing


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Into a blind darkness they enter who follow after the Ignorance,
they as if into a greater darkness enter who devote themselves
to the Knowledge alone. -- Isha Upanishad
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