________________________________
From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> on behalf of James Almer
<jamr...@gmail.com>
Sent: Sunday, October 4, 2020 3:07 AM
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 6:12 PM, Nachiket Tarate wrote:
> 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 ?
Yes.
Also please, don't top post in this list. Write below the paragraph
you're replying to.
Okay, Thanks !
I will resubmit this patch.
Meanwhile, will you please review my first patch:
[PATCH 1/2] libavcodec/adts_header: add frame_length field and avpriv function
to parse AAC ADTS header ?
> ________________________________
> 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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>
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