[Libva] [RFC PATCH Libva-intel-driver 1/6] H264_Encoding: Parse the packed header data from user to fix the hacked code of HW skip bytes
Gwenole Beauchesne
gb.devel at gmail.com
Tue May 20 23:26:55 PDT 2014
Hi Yakui,
Thanks for working on this. Additional comments.
2014-05-21 7:51 GMT+02:00 Zhao, Yakui <yakui.zhao at intel.com>:
> When the packed header data from user is inserted into the coded clip, it uses
> the hacked code to check the number of HW skip emulation bytes. This is wrong.
> So fix it.
> Of course if the packed header data is generated by the driver, it is
> unnecessary to check it and it can still use the pre-defined number of HW
> skip bytes.
>
> Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
> ---
> src/gen6_mfc_common.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 55 insertions(+), 3 deletions(-)
>
> diff --git a/src/gen6_mfc_common.c b/src/gen6_mfc_common.c
> index 33b9d55..f497e75 100644
> --- a/src/gen6_mfc_common.c
> +++ b/src/gen6_mfc_common.c
> @@ -405,6 +405,53 @@ void intel_mfc_brc_prepare(struct encode_state *encode_state,
> }
> }
>
> +static int intel_avc_find_skipemulcnt(unsigned char *buf, int bits_length)
> +{
> + int i, found;
> + int leading_zero_cnt, byte_length, zero_byte;
> + int nal_unit_type;
> + int skip_cnt = 0;
> +
> +#define NAL_UNIT_TYPE_MASK 0x1f
> +
> + byte_length = ALIGN(bits_length, 32) >> 3;
> +
> +
> + leading_zero_cnt = 0;
> + found = 0;
> + for(i = 0; i < byte_length - 4; i++) {
> + if (((buf[i] == 0) && (buf[i + 1] == 0) && (buf[i + 2] == 1)) ||
> + ((buf[i] == 0) && (buf[i + 1] == 0) && (buf[i + 2] == 0) && (buf[i + 3] == 1))) {
> + found = 1;
> + break;
> + }
> + leading_zero_cnt++;
> + }
> + if (!found) {
> + /* warning message is complained. But anyway it will be inserted. */
> + WARN_ONCE("Invalid packed header data. "
> + "Can't find the 000001 start_prefix code\n");
> + return 0;
> + }
> + i = leading_zero_cnt;
> +
> + zero_byte = 0;
> + if (!((buf[i] == 0) && (buf[i + 1] == 0) && (buf[i + 2] == 1)))
> + zero_byte = 1;
> +
> + skip_cnt = leading_zero_cnt + zero_byte + 3;
> +
> + /* the unit header byte is accounted */
> + nal_unit_type = (buf[skip_cnt]) & NAL_UNIT_TYPE_MASK;
> + skip_cnt += 1;
> +
> + if (nal_unit_type == 14 || nal_unit_type == 20) {
> + /* more unit header bytes are accounted for MVC/SVC */
> + skip_cnt += 3;
> + }
> + return skip_cnt;
> +}
> +
> void intel_mfc_avc_pipeline_header_programing(VADriverContextP ctx,
> struct encode_state *encode_state,
> struct intel_encoder_context *encoder_context,
Well, actually, what I meant was:
1. Skip the leading zeros. Really, i.e. even for the part submitted to the HW.
2. Start counting bytes to skip from this new offset.
Reason: the HW supports a limited range of Skip emul bytes. So, if you
skip the leading zeros, you can always fulfill this condition.
Otherwise, you risk an overflow.
Since it is a VA-API requirement for packed headers to contain the
start code prefix, you could split that up into:
1. Search for the start code prefix (sc_offset) ;
2. Determine the nalUnitHeaderBytes count.
Based on (1), you can safely make the sc_offset the new origin of the
buffer to submit + reduce the programmed size accordingly.
And (1) could also be shared with other codecs.
Another thing, also include MVCD. i.e. nal_unit_type == 21, IIRC.
Thanks,
Gwenole.
> @@ -413,6 +460,7 @@ void intel_mfc_avc_pipeline_header_programing(VADriverContextP ctx,
> struct gen6_mfc_context *mfc_context = encoder_context->mfc_context;
> int idx = va_enc_packed_type_to_idx(VAEncPackedHeaderH264_SPS);
> unsigned int rate_control_mode = encoder_context->rate_control_mode;
> + unsigned int skip_emul_byte_cnt;
>
> if (encode_state->packed_header_data[idx]) {
> VAEncPackedHeaderParameterBuffer *param = NULL;
> @@ -423,12 +471,13 @@ void intel_mfc_avc_pipeline_header_programing(VADriverContextP ctx,
> param = (VAEncPackedHeaderParameterBuffer *)encode_state->packed_header_param[idx]->buffer;
> length_in_bits = param->bit_length;
>
> + skip_emul_byte_cnt = intel_avc_find_skipemulcnt((unsigned char *)header_data, length_in_bits);
> mfc_context->insert_object(ctx,
> encoder_context,
> header_data,
> ALIGN(length_in_bits, 32) >> 5,
> length_in_bits & 0x1f,
> - 5, /* FIXME: check it */
> + skip_emul_byte_cnt,
> 0,
> 0,
> !param->has_emulation_bytes,
> @@ -446,12 +495,14 @@ void intel_mfc_avc_pipeline_header_programing(VADriverContextP ctx,
> param = (VAEncPackedHeaderParameterBuffer *)encode_state->packed_header_param[idx]->buffer;
> length_in_bits = param->bit_length;
>
> + skip_emul_byte_cnt = intel_avc_find_skipemulcnt((unsigned char *)header_data, length_in_bits);
> +
> mfc_context->insert_object(ctx,
> encoder_context,
> header_data,
> ALIGN(length_in_bits, 32) >> 5,
> length_in_bits & 0x1f,
> - 5, /* FIXME: check it */
> + skip_emul_byte_cnt,
> 0,
> 0,
> !param->has_emulation_bytes,
> @@ -469,12 +520,13 @@ void intel_mfc_avc_pipeline_header_programing(VADriverContextP ctx,
> param = (VAEncPackedHeaderParameterBuffer *)encode_state->packed_header_param[idx]->buffer;
> length_in_bits = param->bit_length;
>
> + skip_emul_byte_cnt = intel_avc_find_skipemulcnt((unsigned char *)header_data, length_in_bits);
> mfc_context->insert_object(ctx,
> encoder_context,
> header_data,
> ALIGN(length_in_bits, 32) >> 5,
> length_in_bits & 0x1f,
> - 5, /* FIXME: check it */
> + skip_emul_byte_cnt,
> 0,
> 0,
> !param->has_emulation_bytes,
> --
> 1.7.12-rc1
>
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