quietvoid:
> On Fri, Dec 31, 2021 at 9:16 PM Andreas Rheinhardt
> <andreas.rheinha...@outlook.com> wrote:
>>
>> quietvoid:
>>> Both parse/write implementations are based on mov/movenc.
>>>
>>> This only adds support for the "Dolby Vision configuration box".
>>> Other configuration boxes, such as
>>> "Dolby Vision enhancement layer configuration box" are not supported.
>>>
>>> The new functions will be used to implement parsing/writing the DOVI config
>>> for Matroska, as well as to refactor both mov/movenc to use dovi_isom
>>> functions.
>>>
>>> Signed-off-by: quietvoid <tcchlis...@gmail.com>
>>> ---
>>> libavformat/dovi_isom.c | 118 ++++++++++++++++++++++++++++++++++++++++
>>> libavformat/dovi_isom.h | 35 ++++++++++++
>>> 2 files changed, 153 insertions(+)
>>> create mode 100644 libavformat/dovi_isom.c
>>> create mode 100644 libavformat/dovi_isom.h
>>>
>>> diff --git a/libavformat/dovi_isom.c b/libavformat/dovi_isom.c
>>> new file mode 100644
>>> index 0000000000..262d7e37ba
>>> --- /dev/null
>>> +++ b/libavformat/dovi_isom.c
>>> @@ -0,0 +1,118 @@
>>> +/*
>>> + * DOVI ISO Media common code
>>> + *
>>> + * Copyright (c) 2020 Vacing Fang <vacingf...@tencent.com>
>>> + * Copyright (c) 2021 quietvoid
>>> + *
>>> + * 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/dovi_meta.h"
>>> +
>>> +#include "libavcodec/put_bits.h"
>>> +
>>> +#include "avformat.h"
>>> +#include "dovi_isom.h"
>>> +
>>> +int ff_isom_parse_dvcc_dvvc(AVFormatContext *s, AVStream *st, const
>>> uint8_t *buf_ptr, uint64_t size)
>>> +{
>>> + uint32_t buf;
>>> + AVDOVIDecoderConfigurationRecord *dovi;
>>> + size_t dovi_size;
>>> + int ret;
>>> +
>>> + if (size > (1 << 30) || size < 4)
>>> + return AVERROR_INVALIDDATA;
>>> +
>>> + dovi = av_dovi_alloc(&dovi_size);
>>> + if (!dovi)
>>> + return AVERROR(ENOMEM);
>>> +
>>> + dovi->dv_version_major = *buf_ptr++; // 8 bits
>>> + dovi->dv_version_minor = *buf_ptr++; // 8 bits
>>> +
>>> + buf = *buf_ptr++ << 8;
>>> + buf |= *buf_ptr++;
>>> +
>>> + dovi->dv_profile = (buf >> 9) & 0x7f; // 7 bits
>>> + dovi->dv_level = (buf >> 3) & 0x3f; // 6 bits
>>> + dovi->rpu_present_flag = (buf >> 2) & 0x01; // 1 bit
>>> + dovi->el_present_flag = (buf >> 1) & 0x01; // 1 bit
>>> + dovi->bl_present_flag = buf & 0x01; // 1 bit
>>> +
>>> + // Has enough remaining data
>>> + if (size >= 5) {
>>> + dovi->dv_bl_signal_compatibility_id = ((*buf_ptr++) >> 4) & 0x0f;
>>> // 4 bits
>>> + } else {
>>> + // 0 stands for None
>>> + // Dolby Vision V1.2.93 profiles and levels
>>> + dovi->dv_bl_signal_compatibility_id = 0;
>>> + }
>>> +
>>> + ret = av_stream_add_side_data(st, AV_PKT_DATA_DOVI_CONF,
>>> + (uint8_t *)dovi, dovi_size);
>>> + if (ret < 0) {
>>> + av_free(dovi);
>>> + return ret;
>>> + }
>>> +
>>> + av_log(s, AV_LOG_TRACE, "DOVI in dvcC/dvvC/dvwC box, version: %d.%d,
>>> profile: %d, level: %d, "
>>> + "rpu flag: %d, el flag: %d, bl flag: %d, compatibility id:
>>> %d\n",
>>> + dovi->dv_version_major, dovi->dv_version_minor,
>>> + dovi->dv_profile, dovi->dv_level,
>>> + dovi->rpu_present_flag,
>>> + dovi->el_present_flag,
>>> + dovi->bl_present_flag,
>>> + dovi->dv_bl_signal_compatibility_id);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +void ff_isom_put_dvcc_dvvc(AVFormatContext *s, uint8_t
>>> out[ISOM_DVCC_DVVC_SIZE],
>>> + AVDOVIDecoderConfigurationRecord *dovi)
>>> +{
>>> + PutBitContext pb;
>>> +
>>> + init_put_bits(&pb, out, ISOM_DVCC_DVVC_SIZE);
>>> +
>>> + put_bits(&pb, 8, dovi->dv_version_major);
>>> + put_bits(&pb, 8, dovi->dv_version_minor);
>>> + put_bits(&pb, 7, dovi->dv_profile);
>>> + put_bits(&pb, 6, dovi->dv_level);
>>> + put_bits(&pb, 1, dovi->rpu_present_flag);
>>> + put_bits(&pb, 1, dovi->el_present_flag);
>>> + put_bits(&pb, 1, dovi->bl_present_flag);
>>> + put_bits(&pb, 4, dovi->dv_bl_signal_compatibility_id);
>>
>> There is a slight problem with the last six values: They come from the
>> user and therefore must not be trusted to be within the range they are
>> supposed to be. (The put_bits API uses an av_assert2 to check that
>> the values to be written actually fit into the amount of bits that is
>> used to write them.) So I suggest you use !! for the flags and
>> appropriate masks for dv_profile, dv_level and
>> dv_bl_signal_compatibility_id.
>
> Thanks. I used the same masks as in the read function.
>
The current code is also dangerous (just a bit less than this version of
your patchset): If dv_profile & 128 is set (which it mustn't), then the
avio_wb16() will run into the av_assert2 in avio_w8() (if assert-level
is >=2).
(And dovi->dv_bl_signal_compatibility_id << 28 would be UB in case
dv_bl_signal_compatibility_id & 0xF8 is != 0.)
- Andreas
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