On 12/10/16 10:38, Anton Khirnov wrote:
> Quoting Mark Thompson (2016-10-10 21:54:35)
>> Only works if packed headers are supported, where we can know the
>> output before generating the first frame.
>> ---
>> Added padding; fail harder; informative comment in header.
>>
>> Not sure how to do this in the non-packed-header case - we could just
>> invoke this anyway, but the result is unlikely to precisely match what
>> the encoder then produces.
>
> I guess we shouldn't then -- creating corrupted files is evil. At least
> in avconv we can now use the extract_extradata bitstream filter (once it
> goes in) to get the extradata from the first packet.
Ok. (Later, the bitstream filter could be applied automatically by the encoder
when it knows it doesn't have packed header support?)
>>
>> libavcodec/vaapi_encode.c | 22 ++++++++++++++++++++++
>> libavcodec/vaapi_encode.h | 2 ++
>> 2 files changed, 24 insertions(+)
>>
>> diff --git a/libavcodec/vaapi_encode.c b/libavcodec/vaapi_encode.c
>> index b600a00..4dc1f50 100644
>> --- a/libavcodec/vaapi_encode.c
>> +++ b/libavcodec/vaapi_encode.c
>> @@ -1399,6 +1399,28 @@ av_cold int ff_vaapi_encode_init(AVCodecContext
>> *avctx)
>> // where it actually overlaps properly, though.)
>> ctx->issue_mode = ISSUE_MODE_MAXIMISE_THROUGHPUT;
>>
>> + if (ctx->va_packed_headers & VA_ENC_PACKED_HEADER_SEQUENCE &&
>> + ctx->codec->write_sequence_header) {
>> + char data[MAX_PARAM_BUFFER_SIZE];
>> + size_t bit_len = 8 * sizeof(data);
>> +
>> + err = ctx->codec->write_sequence_header(avctx, data, &bit_len);
>> + if (err < 0) {
>> + av_log(avctx, AV_LOG_ERROR, "Failed to write sequence header "
>> + "for extradata: %d.\n", err);
>> + goto fail;
>> + } else {
>> + avctx->extradata_size = bit_len / 8;
>
> Round up? Or is this guaranteed to be byte-aligned (in which case why is
> it not in bytes in the first place)?
I'll add the round up.
It is byte-aligned in all current cases; the length is in bits to be consistent
with the other header-writing functions, which can produce non-byte-aligned
output.
Thanks,
- Mark
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