On Fri, 25 Aug 2023, Steven Liu wrote:
Martin Storsjö <[email protected]> 于2023年8月25日周五 17:38写道：On Fri, 25 Aug 2023, Steven Liu wrote: >> > + list_len = (fourcc_str_len + 1) / 5; >> > + // write the fourCcList field name >> > + ff_amf_write_field_name(&p, "fourCcList"); >> > + >> > + // write the fourcc array length >> > + ff_amf_write_array_start(&p, list_len); >> > + >> > + while(fourcc_data - rt->enhanced_codecs < fourcc_str_len) { >> > + unsigned char fourcc[5]; >> > + switch (AV_RN32(fourcc_data)) { >> > + case MKTAG('h', 'v', 'c', '1'): >> >> This feels a bit convoluted to use AV_RN32 + MKTAG on data that is already >> just a string - just using strncmp(fourcc_data, "hvc1", 4) would work just > I want use strncmp at first, but i think strncmp will slower than > switch uint32_t value, so i chose use uint32_t. or should i use > strncmp? Yes, strncmp will be slower than switching on an uint32_t - but this isn't really performance sensitive code. We do this once only, on startup, on a handful of fourccs. So I believe code clarity is more important than absolute performance here.Okay, i use strncasecmp next version patch.
I don't see a need for this to be case insensitive?
But i must told you, I think MKTAG is clarity than use if+strncmp to me, Because there looks like a fourcc codec list align code block.
If you prefer MKTAG for clarity, then I guess the current solution is fine here for me as well - it's not a hard opinion from me. Let's see if someone else wants to comment on it first maybe.
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