So you want me to change ff_ac3_sample_rate_tab to avpriv_ac3_sample_rate_tab
and get channel count using av_get_channel_layout_nb_channels(). Is my
understanding correct ?
________________________________
From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> on behalf of James Almer
<jamr...@gmail.com>
Sent: Saturday, October 3, 2020 11:04 PM
To: ffmpeg-devel@ffmpeg.org <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 2/2] libavcodec/ac3_parser: add avpriv
function to parse EC3SpecificBox (dec3)
On 10/3/2020 2:30 PM, Nachiket Tarate wrote:
> Actually names of 2 tables ff_ac3_sample_rate_tab and ff_ac3_channels_tab
> need to be changed in order to access them from libavformat.
> There would be changes in multiple files in which these tables have been used
> currently. Is that fine ?
You can use av_get_channel_layout_nb_channels() to get channel count
from the output of avpriv_ac3_channel_layout_tab[]. Same as
mov_read_dec3() in libavformat/mov.c does.
>
> ________________________________
> From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> on behalf of James Almer
> <jamr...@gmail.com>
> Sent: Friday, October 2, 2020 7:48 PM
> To: ffmpeg-devel@ffmpeg.org <ffmpeg-devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 2/2] libavcodec/ac3_parser: add avpriv
> function to parse EC3SpecificBox (dec3)
>
> On 10/2/2020 10:10 AM, Nachiket Tarate wrote:
>> This will be used by HLS demuxer for SAMPLE-AES decryption.
>>
>> Signed-off-by: Nachiket Tarate <nachiket.tar...@outlook.com>
>> ---
>> libavcodec/ac3_parser.c | 47 ++++++++++++++++++++++++++++++++
>> libavcodec/ac3_parser_internal.h | 4 +++
>> 2 files changed, 51 insertions(+)
>>
>> diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c
>> index ba171653ef..a8fdde0ff9 100644
>> --- a/libavcodec/ac3_parser.c
>> +++ b/libavcodec/ac3_parser.c
>> @@ -2,6 +2,7 @@
>> * AC-3 parser
>> * Copyright (c) 2003 Fabrice Bellard
>> * Copyright (c) 2003 Michael Niedermayer
>> + * Copyright (c) 2020 Nachiket Tarate
>> *
>> * This file is part of FFmpeg.
>> *
>> @@ -172,6 +173,47 @@ int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const
>> uint8_t *buf,
>> return get_bits_count(&gb);
>> }
>>
>> +/*
>> + * Parse 'dec3' EC3SpecificBox
>> + */
>> +int avpriv_eac3_parse_dec3(AC3HeaderInfo **phdr, const uint8_t *buf, size_t
>> size)
>> +{
>> + GetBitContext gb;
>> + AC3HeaderInfo *hdr;
>> + int err;
>> +
>> + int data_rate, fscod, acmod, lfeon;
>> +
>> + if (!*phdr)
>> + *phdr = av_mallocz(sizeof(AC3HeaderInfo));
>> + if (!*phdr)
>> + return AVERROR(ENOMEM);
>> + hdr = *phdr;
>> +
>> + err = init_get_bits8(&gb, buf, size);
>> + if (err < 0)
>> + return AVERROR_INVALIDDATA;
>> +
>> + data_rate = get_bits(&gb, 13);
>> + skip_bits(&gb, 3);
>> + fscod = get_bits(&gb, 2);
>> + skip_bits(&gb, 10);
>> + acmod = get_bits(&gb, 3);
>> + lfeon = get_bits(&gb, 1);
>> +
>> + hdr->sample_rate = ff_ac3_sample_rate_tab[fscod];
>
> Why not instead just make this array avpriv_? Everything else can be
> done within libavformat. See mov_read_dec3() in mov.c
>
>> +
>> + hdr->channels = ff_ac3_channels_tab[acmod] + lfeon;
>> +
>> + hdr->channel_layout = avpriv_ac3_channel_layout_tab[acmod];
>> + if (lfeon)
>> + hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
>> +
>> + hdr->bit_rate = data_rate*1000;
>> +
>> + return 0;
>> +}
>> +
>> int av_ac3_parse_header(const uint8_t *buf, size_t size,
>> uint8_t *bitstream_id, uint16_t *frame_size)
>> {
>> @@ -256,6 +298,11 @@ int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const
>> uint8_t *buf,
>> return AVERROR(ENOSYS);
>> }
>>
>> +int avpriv_eac3_parse_dec3(AC3HeaderInfo **phdr, const uint8_t *buf, size_t
>> size)
>> +{
>> + return AVERROR(ENOSYS);
>> +}
>> +
>> int av_ac3_parse_header(const uint8_t *buf, size_t size,
>> uint8_t *bitstream_id, uint16_t *frame_size)
>> {
>> diff --git a/libavcodec/ac3_parser_internal.h
>> b/libavcodec/ac3_parser_internal.h
>> index 3648802a73..0388a5bb5e 100644
>> --- a/libavcodec/ac3_parser_internal.h
>> +++ b/libavcodec/ac3_parser_internal.h
>> @@ -38,5 +38,9 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo
>> *hdr);
>>
>> int avpriv_ac3_parse_header(AC3HeaderInfo **hdr, const uint8_t *buf,
>> size_t size);
>> +/*
>> + * Parse 'dec3' EC3SpecificBox
>> + */
>> +int avpriv_eac3_parse_dec3(AC3HeaderInfo **phdr, const uint8_t *buf, size_t
>> size);
>>
>> #endif /* AVCODEC_AC3_PARSER_INTERNAL_H */
>>
>
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