Niklas Haas:
> From: Niklas Haas <g...@haasn.dev>
>
> Instead of the nal_prefix, this profile inside wraps the RPU inside an
> EMDF header, as specified in ETSI TS 102 366. This particular usage is
> supposedly specified in ETSI TS 103 572, at least according to European
> Patent EP 3 588 964 A1, but I could not find any references to DV RPUs
> in the former.
>
> It's worth pointing out that the EMDF container is not byte-aligned,
> meaning that payloads are delivered at arbitrary byte boundaries. Hence
> the reason for doing it inside ff_dovi_rpu_parse, which already uses
> a bitstream reader, rather than splitting off the container in
> a separate stage. (Plus, we hard-code the DV-specific payload ID)
>
> Magic values were taken from a combination of the sources below, all of
> which agree about what the specific EMDF header should look like. In
> fact, they all hard-code a very *specific* header sequence, but I wanted
> to go the extra mile and at least properly skip the variable fields
> - even though the non-existent Dolby Vision specification probably
> specifies that they all must be 0. This is probably overkill.
>
> Validated and tested using sample files from the merge request linked
> below.
>
> Relevant links:
> -
> https://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.04.01_60/ts_102366v010401p.pdf
> -
> https://patentimages.storage.googleapis.com/8a/0b/da/28294acaed2182/EP3588964A1.pdf
> -
> https://www.etsi.org/deliver/etsi_ts/103500_103599/103572/01.03.01_60/ts_103572v010301p.pdf
> -
> https://github.com/rockchip-linux/mpp/blob/fdeb8c378b79d4b4ef80457e4431815de89dc417/mpp/codec/dec/av1/av1d_cbs.c#L2378
> -
> https://github.com/elginsk8r/android_kernel_amlogic_linux-4.9/blob/23a4c38bf06ef34821e476a8edddbf9213712c8a/drivers/amlogic/media/enhancement/amdolby_vision/amdolby_vision.c#L5638
> - https://gitlab.com/mbunkus/mkvtoolnix/-/merge_requests/2254
> ---
> libavcodec/dovi_rpu.c | 68 +++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 65 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/dovi_rpu.c b/libavcodec/dovi_rpu.c
> index a6b23f4dd11..c7cdd65a2f2 100644
> --- a/libavcodec/dovi_rpu.c
> +++ b/libavcodec/dovi_rpu.c
> @@ -174,6 +174,18 @@ static inline int64_t get_se_coef(GetBitContext *gb,
> const AVDOVIRpuDataHeader *
> return 0; /* unreachable */
> }
>
> +static inline unsigned get_variable_bits(GetBitContext *gb, int n)
> +{
> + unsigned int value = get_bits(gb, n);
> + int read_more = get_bits1(gb);
> + while (read_more) {
> + value = (value + 1) << n;
> + value += get_bits(gb, n);
Using |= is more appropriate.
> + read_more = get_bits1(gb);
> + };
The ';' is a null statement.
> + return value;
> +}
> +
> #define VALIDATE(VAR, MIN, MAX)
> \
> do {
> \
> if (VAR < MIN || VAR > MAX) {
> \
> @@ -200,9 +212,59 @@ int ff_dovi_rpu_parse(DOVIContext *s, const uint8_t
> *rpu, size_t rpu_size)
> if ((ret = init_get_bits8(gb, rpu, rpu_size)) < 0)
> return ret;
>
> - /* RPU header, common values */
> - nal_prefix = get_bits(gb, 8);
> - VALIDATE(nal_prefix, 25, 25);
> + /* Container header */
> + if (s->dv_profile == 10 /* dav1.10 */) {
> + /* DV inside AV1 re-uses EMDF container, parse header */
> + int emdf_version, key_id, emdf_payload_id, emdf_payload_size,
> smploffste;
> + emdf_version = get_bits(gb, 2);
> + if (emdf_version == 3)
> + emdf_version += get_variable_bits(gb, 2);
> + key_id = get_bits(gb, 3);
> + if (key_id == 7)
> + key_id += get_variable_bits(gb, 3);
> + emdf_payload_id = get_bits(gb, 5);
> + if (emdf_payload_id == 0x1F)
> + emdf_payload_id += get_variable_bits(gb, 5);
> +
> + /* Magic values taken from amlogic and rockchip drivers, and also
> + * match values found in practice (and validated in hardware) */
> + VALIDATE(key_id, 6, 6);
> + VALIDATE(emdf_payload_id, 256, 256);
> +
> + /* Note: In theory, there could be multiple payloads, and we should
> + * skip over the unused payloads until we find the one we're
> interested
> + * in. But this capability does not seem to be used in practice, so
> + * the DV-specific usage of EMDF probably requires only one payload
> + * per T.35 OBU */
> +
> + /* Skip emdf_payload_config() */
> + if ((smploffste = get_bits1(gb)))
> + skip_bits(gb, 11 + 1);
> + if (get_bits1(gb)) /* duratione */
> + get_variable_bits(gb, 11);
> + if (get_bits1(gb)) /* groupide */
> + get_variable_bits(gb, 2);
> + if (get_bits1(gb)) /* codecdatae */
> + skip_bits(gb, 8);
> + if (!get_bits1(gb)) { /* discard_unknown_payload */
> + int payload_frame_aligned;
> + if (!smploffste) {
> + if ((payload_frame_aligned = get_bits1(gb)))
> + skip_bits(gb, 1 + 1);
> + }
> + if (smploffste || payload_frame_aligned)
> + skip_bits(gb, 5 + 2);
> + }
> +
> + emdf_payload_size = get_variable_bits(gb, 8);
> + if (emdf_payload_size * 8 > get_bits_left(gb))
> + return AVERROR_INVALIDDATA;
> + } else {
> + nal_prefix = get_bits(gb, 8);
> + VALIDATE(nal_prefix, 25, 25);
> + }
> +
> + /* RPU header */
> rpu_type = get_bits(gb, 6);
> if (rpu_type != 2) {
> av_log(s->logctx, AV_LOG_WARNING, "Unrecognized RPU type "
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